Electronic telecommunications articles comprising crosslinked fluoropolymers and methods

ABSTRACT

Electronic telecommunication articles are described comprising a crosslinked fluoropolymer layer. In typical embodiments, the crosslinked fluoropolymer layer is a substrate, patterned (e.g. photoresist) layer, insulating layer, passivation layer, cladding, protective layer, or a combination thereof. Also describes are methods of making an electronic telecommunications article and method of forming a patterned fluoropolymer layer. The fluoropolymer preferably comprises at least 80, 85, or 90% by weight of polymerized units of perfluorinated monomers and cure sites selected from nitrile, iodine, bromine, and chlorine. Illustrative electronic communication articles include integrated circuits, printed circuit boards, antennas, and optical fiber cables. Fluoropolymer compositions are also described.

SUMMARY

In one embodiment, electronic telecommunication articles are describedcomprising a crosslinked fluoropolymer layer. In typical embodiments,the crosslinked fluoropolymer layer is a substrate, patterned (e.g.photoresist) layer, insulating layer, passivation layer, cladding,protective layer, or a combination thereof.

In another embodiment, a method of making an electronictelecommunications article is described comprising providing a film orcoating solution comprising a fluoropolymer; and applying the film orcoating solution to a component of an electronic telecommunicationsarticle.

The coating solution typically further comprises a fluorinated solvent.The method further comprises crosslinking the fluoropolymer by exposureto heat, actinic radiation, or a combination thereof.

In another embodiment, a method of forming a patterned fluoropolymerlayer is described comprising applying a fluoropolymer film to asubstrate; selectively crosslinking portions of the fluoropolymer filmby exposure to actinic radiation; and removing uncrosslinked portions ofthe fluoropolymer film.

In each of these embodiments, the fluoropolymer preferably comprises atleast 80, 85, or 90% by weight of polymerized units of perfluorinatedmonomers and cure sites selected from nitrile, iodine, bromine, andchlorine.

Illustrative electronic communication articles include integratedcircuits, printed circuit boards, antennas, and optical fiber cables.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional diagram of forming a patternedfluoropolymer layer by photolithography in an illustrative embodiment ofthe manufacture of an integrated circuit (IC).

FIG. 2 is a perspective view of an illustrative printed circuit board(PCB) including integrated circuits:

FIGS. 3A and 3B are cross-sectional diagrams of illustrativefluoropolymer passivation and insulating layers.

FIG. 4 is a plan view of an illustrative antenna of a mobile computerdevice.

FIGS. 5A and 5B are perspective views of illustrative antennas of atelecommunications tower.

FIG. 6 is a cross-sections diagram of an illustrative optical fibercable.

DETAILED DESCRIPTION

Presently described are certain fluoropolymer compositions (e.g. filmsand coatings) for use in electronic telecommunication articles. As usedherein, electronic refers to devices using the electromagnetic spectrum(e.g. electrons, photons); whereas telecommunication is the transmissionof signs, signals, messages, words, writings, images and sounds orinformation of any nature by wire, radio, optical or otherelectromagnetic systems.

Polyimide material are used extensively in the electronictelecommunications industry. The structure ofpoly-oxydiphenylene-pyromellitimide, “Kapton” is as follows:

Polyimide films exhibited good insulating properties with dielectricconstants values in the range of 2.78-3.48 and dielectric loss between0.01 and 0.03 at 1 Hz at room temperature.

Perfluoropolymers can have substantially lower dielectric constants anddielectric loss properties than polyimides which is particularlyimportant for fifth generation cellular network technology (“5G”)articles. For example, crosslinked fluoropolymer compositions describedherein can have a dielectric constant (Dk) of less than 2.75, 2.70,2.65, 2.60, 2.55, 2.50, 2.45, 2.40, 2.35, 2.30, 2.25, 2.20, 2.15, 2.10,2.05, 2.00, or 1.95. In some embodiments, the dielectric constant is atleast 2.02, 2.03, 2.04, 2.05. Further, the crosslinked fluoropolymercompositions described herein can have a low dielectric loss, typicallyless than 0.01, 0.009, 0.008, 0.007, 0.006, 0.005, 0.004, 0.003, 0.002,0.001, 0.0009, 0.0008, 0.0007, 0.0006, 0.0005, 0.0004, 0.0003. In someembodiments, the dielectric loss is at least 0.00022, 0.00023, 0.00024,0.00025. The dielectric properties (e.g. constant and loss) can bedetermined according to the test method described in the examples. Asthe number of non-fluorine atoms increases (e.g. number ofcarbon-hydrogen and/or carbon-oxygen bonds increases) the dielectricconstant and dielectric loss also typically increases.

However, perfluoropolymers have not been used in place of polyimides isvarious electronic telecommunications articles are least in part by thelack of perfluoropolymer materials that can be crosslinked by exposureto actinic and more preferably ultraviolet radiation. Crosslinkedperfluoropolymer materials can have improved mechanical properties incomparison to uncrosslinked perfluoropolymer materials. Hence, theperfluoropolymer compositions described are suitable for use in place ofpolyimides in various electronic telecommunication articles.

In one embodiment, the electronic telecommunication article is anintegrated circuit or in other words a silicon chip or microchip, i.e. amicroscopic electronic circuit array formed by the fabrication ofvarious electrical and electronic components (resistors, capacitors,transistors, and so on) on a semiconductor material (silicon) wafer.

In one embodiment, the fluoropolymer composition described herein can beused to form a patterned (e.g. photoresist) layer. Fluoropolymercompositions as described herein can be used as a negative photoresistin a variety of fabrication techniques. In some embodiments, (e.g.sacrificial) photoresist materials are etched away and do not remain inthe finished article. In other embodiments, the photoresist material maybe present in the finished article. Various integrated circuit designshave been described in the literature.

With reference to FIG. 1 , in one embodiment, a method of forming apatterned fluoropolymer layer is described comprising applying afluoropolymer film 100 to a substrate (e.g. silicon wafer 120 or thepassivation (e.g. SiO₂) layer 125 coated surface thereof); selectivelycrosslinking portions of the fluoropolymer film by exposure to actinicradiation; and removing uncrosslinked portions of the fluoropolymerfilm.

In some embodiments, the method further comprises providing a mask (e.g.photomask) 130 having one or more opening between the fluoropolymer film100 and a source of actinic (e.g. e-beam or UV) radiation 140 andexposing the fluoropolymer film to actinic radiation through at leastone opening of the mask.

As known in the art, the mask includes actinic energy (e.g. UV light)transmitting portions and portions that are non-transmitting of actinicenergy (e.g. UV light). Photomasks typically comprise a transparentsubstrate, with a non-transmitting mask pattern on the surface of thesubstrate. The substrate is typically (e.g. highly pure quartz) glass,that is transparent to the illumination (i.e. wavelengths and intensity)of the photolithography process employed. The mask is typically preparedby selective deposition or selective etching of a mask material. Commonnon-light-transmitting mask materials include chrome metal, iron oxide,molybdenum silicide, etc., as known in the art.

After exposure, the fluoropolymer film comprises a patternedfluoropolymer layer comprising portions of cured or in other wordscrosslinked fluoropolymer 150 and portions of uncured or in other wordsuncrosslinked fluoropolymer 175.

In some embodiments, the method further comprises removing portions ofuncrosslinked fluoropolymer film by dissolving the uncrosslinkedportions in a solvent 160 (e.g. washing the fluoropolymer film withfluorinated solvent). The portions of cured or in other wordscrosslinked fluoropolymer 150 remains on the surface of the substrate asa patterned fluoropolymer layer. In this embodiment, the substrate or(e.g. SiO₂) coated surface thereof that comes in contact with thesolvent is substantially insoluble in the solvent utilized for removingthe uncrosslinked portions of the fluoropolymer film. In favoredembodiments, the solvent is a fluorinated solvent.

In some embodiments, particularly when it is desirable to apply a thinfluoropolymer film to the substrate, the method comprises applying acoating solution (e.g. spin coating) to the substrate, wherein thecoating solution comprises a fluorinated solvent and a fluoropolymer. Insome embodiments, the fluoropolymer preferably comprises predominantlypolymerized units of perfluorinated monomers and cure sites. The coatingfurther comprises a curing agent that reacts with the cure sites in thepresence of actinic (e.g. UV) radiation thereby crosslinking thefluoropolymer. The method typically comprises removing the fluorinatedsolvent (e.g. by evaporation). In this embodiment, the substrate or(e.g. SiO₂) coated surface thereof that comes in contact with thesolvent is substantially insoluble in the fluorinated solvent of thecoating solution. The fluorinated solvent for removing the uncrosslinkedportions of the fluoropolymer film and the fluorinated solvent of thecoating solution can be the same or different fluorinated solvents.Further, the method typically comprises recycling, or in other wordsreusing, the fluorinated solvent utilized to remove the uncrosslinkedportions of the fluoropolymer film and/or the fluorinated solvent of thecoating solution.

In other embodiments, the uncured portions 175 may be removed with othersolventless methods, such as laser ablation.

The patterned fluoropolymer layer can be used to fabricate other layerssuch as a circuit of patterned electrode materials. Suitable electrodematerials and deposition methods are known in the art. Such electrodematerials include, for example, inorganic or organic materials, orcomposites of the two. Exemplary electrode materials includepolyaniline, polypyrrole, poly(3,4-ethylenedioxythiophene) (PEDOT) ordoped conjugated polymers, further dispersions or pastes of graphite orparticles of metal such as Au, Ag, Cu, Al, Ni or their mixtures as wellas sputter-coated or evaporated metals such as Cu, Cr, Pt/Pd, Ag, Au,Mg, Ca, Li or mixtures or metal oxides such as indium tin oxide (ITO),F-doped ITO, GZO (gallium doped zinc oxide), or AZO (aluminium dopedzinc oxide). Organometallic precursors may also be used and depositedfrom a liquid phase.

In another embodiment, the fluoropolymer (e.g. photoresist) layer can bedisposed upon a metal (e.g. copper) substrate in the manufacture of aprinted circuit board (PCB). An illustrative perspective view of aprinted circuit board is depicted in FIG. 2 . A printed circuit board,or PCB, is used to mechanically support and electrically connectelectronic components using conductive pathways, tracks or signal tracesetched from (e.g. copper) metal sheets laminated onto a non-conductivesubstrate. Such boards are typically made from an insulating materialsuch as glass fiber reinforced (fiberglass) epoxy resin or paperreinforced phenolic resin. The pathways for electricity are typicallymade from a negative photoresist, as previously described. Thus, in thisembodiment, the crosslinked fluoropolymer is disposed on the surface ofthe (e.g. copper) metal substrate. Portions of uncrosslinkedfluoropolymer are removed to form the conductive (e.g. copper) pathways.Crosslinked fluoropolymer (e.g. photoresist) remain present, disposedbetween the conductive (e.g. copper) pathways of the printed circuitboard. Solder is used to mount components on the surface of theseboards. In some embodiments, the printed circuit board further comprisesintegrated circuits 200, as depicted in FIG. 2 . Printed circuit boardassemblies have an application in almost every electronic articleincluding computers, computer printers, televisions, and cell phones.

In another embodiment, the crosslinked fluoropolymer film describedherein can be utilized as an insulating layer, passivation layer, and/orprotective layer in the manufacture of integrated circuits.

With reference to FIG. 3A, in one embodiment, a thin fluoropolymer film300 (e.g. typically having a thickness less than 50, 40, or 30 nm) canbe disposed on a passivation layer 310 (e.g. SiO₂) disposed on anelectrode patterned 360 silicon chip 320.

With reference to FIG. 3B, in another embodiment, a thickerfluoropolymer film 300 (e.g. typically having a thickness of at least100, 200, 300, 400, 500 nm) can be disposed on an electrode patterned360 silicon chip 320. In this embodiment, the fluoropolymer layer mayfunction as both a passivation layer and an insulating layer.Passivation is the use of a thin coating to provide electrical stabilityby isolating the transistor surface from electrical and chemicalconditions of the environment.

In another embodiment, the crosslinked fluoropolymer film describedherein can be utilized as a substrate for antennas. The antenna of thetransmitter emits (e.g. high frequency) energy into space while theantenna of the receiver catches this and converts it into electricity.

The patterned electrodes of an antenna can also be formed fromphotolithography. Screen printing, flexography, and ink jet printing canalso be utilized to form the electrode pattern as known in the art.Various antenna designs for (e.g. mobile) computing devices (smartphone, tablet, laptop, desktop) have been described in the literature.One representative split ring monopole antenna is depicted in FIG. 4having the following dimensions in microns.

L₁ 38 W₁ 25 L₂ 26 W₂ 18 L₃ 19 W₃ 10.5 L₄ 9.5 W₄ 6.5 L₅ 3 W₅ 2 G₁ 2 G₂0.5

The low dielectric fluoropolymer films and coatings described herein canalso be utilized as insulating and protective layers of transmitterantennas of cell towers and other (e.g. outdoor) structures. There aretwo major types of antennas used in cell towers. FIG. 5A is depicts arepresentative omnidirectional (e.g. dipole) antenna used totransmit/receive in any direction. FIG. 5B is a representativedirectional antenna used to transmit/receive in particular desireddirection only such as horn antennas of circular and rectangular type.

In another embodiment, the low dielectric fluoropolymer compositionsdescribed herein may also be utilized in fiber optic cable. Withreference to FIG. 6 , fiber optic cable typically includes five maincomponents: the core which is typically highly pure (e.g. silica) glass620, cladding 630, coating (e.g. first inner protective layer) 640,strengthening fibers 650, and outer jacket (i.e. second outer protectivelayer) 660. The function of the cladding is to provide a lowerrefractive index at the core interface in order to cause reflectionwithin the core so that light waves are transmitted through the fiber.The coating over the cladding is typically present to reinforce thefiber core, help absorb shocks, and provide extra protection againstexcessive cable bends. The low dielectric fluoropolymer compositionsdescribed herein can be used as the cladding, coating, outer jacket, orcombination thereof.

In other embodiments, the low dielectric fluoropolymer films andcoatings described herein can also be utilized for flexible cables andas an insulating film on magnet wire. For example, in a laptop computer,the cable that connects the main logic board to the display (which mustflex every time the laptop is opened or closed) may be a low dielectricfluoropolymer composition as described herein with copper conductors.

The electronic telecommunication article is typically not a sealingcomponent of equipment used in wafer and chip production.

One of ordinary skill in the art appreciates that the low dielectricfluoropolymer compositions described herein can be utilized in variouselectronic telecommunication articles, particularly in place ofpolyimide, and such utility is not limited to the specific articlesdescribed herein.

The fluoropolymers described herein are copolymers that comprisepredominantly, or exclusively, (e.g. repeating) polymerized unitsderived from two or more perfluorinated comonomers. Copolymer refers toa polymeric material resulting from the simultaneous polymerization oftwo or more monomers. In some embodiments, the comonomers includetetrafluoroethene (TFE) and one or more unsaturated perfluorinated (e.g.alkenyl, vinyl) alkyl ethers.

In some favored embodiments, the one or more unsaturated perfluorinatedalkyl ethers are selected from the general formula:

R_(f)—O—(CF₂)_(n)—CF═CF₂

wherein n is 1 (allyl ether) or 0 (vinyl ether) and R_(f) represents aperfluoroalkyl residue which may be interrupted once or more than onceby an oxygen atom. R_(f) may contain up to 10 carbon atoms, e.g. 1, 2,3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms. Preferably R_(f) contains up to8, more preferably up to 6 carbon atoms and most preferably 3 or 4carbon atoms. In one embodiment R_(f) has 3 carbon atoms. In anotherembodiment R_(f) has 1 carbon atom. R_(f) may be linear or branched, andit may contain or not contain a cyclic unit. Specific examples of R_(f)include residues with one or more ether functions including but notlimited to:

—(CF₂)—O—C₃F₇,

—(CF₂)₂—O—C₂F₅,

—(CF₂)_(r3)—O—CF₃,

—(CF₂—_(O))—C₃F₇,

—(CF₂—O)₂—C₂F₅,

—(CF₂—O)₃—CF₃,

—(CF₂CF₂—O)—C₃F₇,

—(CF₂CF₂—O)₂—C₂F₅,

—(CF₂CF₂—O)₃—CF₃,

Other specific examples for R_(f) include residues that do not containan ether function and include but are not limited to —C₄F₉; —C₃F₇,—C₂F₅, —CF₃, wherein the C₄ and C₃ residues may be branched or linear,but preferably are linear.

Specific examples of suitable perfluorinated alkyl vinyl ethers (PAVE's)and perfluorinated alkyl allyl ethers (PAAE's) include but are notlimited to perfluoro (methyl vinyl) ether (PMVE), perfluoro (ethylvinyl) ether (PEVE), perfluoro (n-propyl vinyl) ether (PPVE-1),perfluoro-2-propoxypropylvinyl ether (PPVE-2),perfluoro-3-methoxy-n-propylvinyl ether, perfluoro-2-methoxy-ethylvinylether, CF₂═CF—O—CF₂—O—C₂F₅, CF₂═CF—O—CF₂—O—C₃F₇,CF₃—(CF₂)₂—O—CF(CF₃)—CF₂—O—CF(CF₃)—CF₂—O—CF═CF₂ and their allyl etherhomologues. Specific examples of allyl ethers include CF₂═CF—CF₂—O—CF₃,CF₂=CF—CF₂—O—C₃F₇, CF₂=CF—CF₂—O—(CF₃)₃—O—CF₃.

Further examples include but are not limited to the vinyl etherdescribed in European patent application EP 1,997,795 B1.

Perfluorinated ethers as described above are commercially available, forexample from Anles Ltd., St. Petersburg, Russia and other companies ormay be prepared according to methods described in U.S. Pat. No.4,349,650 (Krespan) or European Patent 1,997,795, or by modificationsthereof as known to a skilled person.

In some embodiments, the one or more unsaturated perfluorinated alkylethers comprises unsaturated cyclic perfluorinated alkyl ethers, such as2,2-bistrifluoromethyl-4,5-difluoro-1,3 dioxole. In other embodiments,the fluoropolymer is substantially free of unsaturated cyclicperfluorinated alkyl ethers, such as2,2-bistrifluoromethyl-4,5-difluoro-1,3 dioxole. By substantially freeit is meant that the amount is zero or sufficiently low such thefluoropolymer properties are about the same.

In some favored embodiments, the fluoropolymers are derivedpredominantly or exclusively from perfluorinated comonomers includingtetrafluoroethene (TFE) and one or more of the unsaturatedperfluorinated alkyl ethers described above. “Predominantly” as usedherein means at least 80, 85, or 90% by weight based on the total weightof the fluoropolymer, of the polymerized units of the fluoropolymer arederived from such perfluorinated comonomers such as tetrafluoroethene(TFE) and one or more unsaturated perfluorinated alkyl ethers. In someembodiments, the fluoropolymer comprises at least 81, 82, 83, 84, 85,86, 87, 88, 90, 91, 92, 93, 94, 95, 96, or 97% by weight or greater ofsuch perfluorinated comonomers, based on the total weight of thefluoropolymer. The fluoropolymers may contain at least 40, 45, or 50% byweight of polymerized units derived from TFE. In some embodiments, themaximum amount of polymerized units derived from TFE is no greater than60% by weight.

The fluoropolymer typically comprises polymerized units derived from oneor more of the unsaturated perfluorinated alkyl ethers (PAVE) (e.g.PMVE, PAAE or a combination thereof), in an amount of at least 10, 15,20, 25, 30, 45, or 50% by weight, based on the total polymerized monomerunits of the fluoropolymer. In some embodiments, the fluoropolymercomprises no greater than 50, 45, 40, or 35% by weight of polymerizedunits derived from one or more of the unsaturated perfluorinated alkylethers (PMVE, PAAE or a combination thereof), based on the totalpolymerized monomer units of the fluoropolymer. The molar ratio of unitsderived from TFE to the perfluorinated alkly ethers described above maybe, for example, from 1:1 to 5:1. In some embodiments, the molar ratioranges from 1.5:1 to 3:1.

The fluoropolymers may be thermoplastic but, in a preferred embodiment,the fluoropolymer is amorphous. As used herein, amorphous fluoropolymersare materials that contain essentially no crystallinity or possess nosignificant melting point (peak maximum) as determined by differentialscanning calorimetry in accordance with DIN EN ISO 11357-3:2013-04 undernitrogen flow and a heating rate of 10° C./min. Typically, amorphousfluoropolymers have a glass transition temperature (Tg) of less than 26°C., less than 20° C., or less than 0° C., and for example from −40° C.to 20° C., or −50° C. to 15° C., or −55° C. to 10° C. The fluoropolymersmay typically have a Mooney viscosity (ML 1+10 at 121° C.) of from about2 to about 150, for example from 10 to 100, or from 20 to 70. Foramorphous polymers containing cyclic perfluorinated alky ether units,the glass transition temperature is typically at least 70° C., 80° C.,or 90° C., and may range up to 220° C., 250° C., 270° C., or 290° C. TheMFI (297° C./5 kg) is between 0.1-1000 g/10 min.

In other embodiments, the fluoropolymer may have a melt point of lessthan 150° C. or 100° C.

The fluoropolymer is preferably a curable fluoropolymer that containsone or more cure sites. Cure sites are functional groups that react inthe presence of a curing agent or a curing system to cross-link thepolymers. The cure sites are typically introduced by copolymerizingcure-site monomers, which are functional comonomers already containingthe cure sites or precursors thereof. One indication of crosslinking isthat the dried and cured coating composition was not soluble in thefluorinated solvent of the coating.

The cure sites may be introduced into the polymer by using cure sitemonomers, i.e. functional monomers as will be described below,functional chain-transfer agents and starter molecules. Thefluoroelastomers may contain cure sites that are reactive to more thanone class of curing agents.

The curable fluoroelastomers may also contain cure sites in thebackbone, as pendent groups, or cure sites at a terminal position. Curesites within the fluoropolymer backbone can be introduced by using asuitable cure-site monomer. Cure site monomers are monomers containingone or more functional groups that can act as cure sites or contain aprecursor that can be converted into a cure site.

In some embodiments, the cure sites comprise iodine or bromine atoms.

Iodine-containing cure site end groups can be introduced by using aniodine-containing chain transfer agent in the polymerization.Iodine-containing chain transfer agents will be described below ingreater detail. Halogenated redox systems as described below may be usedto introduce iodine end groups.

In addition to iodine cures sites, other cure sites may also be present,for example Br-containing cure sites or cure sites containing one ormore nitrile groups. Br-containing cure sites may be introduced byBr-containing cure-site monomers.

Examples of cure-site comonomers include for instance:

(a) bromo- or iodo-(per)fluoroalkyl-(per)fluorovinylethers, for exampleincluding those having the formula:

ZRf—O—CX═CX₂

wherein each X may be the same or different and represents H or F, Z isBr or I, Rf is a C1-C12 (per)fluoroalkylene, optionally containingchlorine and/or ether oxygen atoms. Suitable examples includeZCF₂—O—CF═CF₂, ZCF₂CF₂—O—CF═CF₂, ZCF₂CF₂CF₂—O—CF═CF₂, CF₃CF═CF₂—O—CF═CF₂or ZCF₂CF₂—O—CF₂CF₂CF₂—O—CF═CF₂ wherein Z represents Br of I; and

(b) bromo- or iodo perfluoroolefins such as those having the formula:

Z′—(Rf)r-CX═CX₂

wherein each X independently represents H or F, Z′ is Br or I, Rf is aC₁-C₁₂ perfluoroalkylene, optionally containing chlorine atoms and r is0 or 1; and

(c) non-fluorinated bromo and iodo-olefins such as vinyl bromide, vinyliodide, 4-bromo-1-butene and 4-iodo-1-butene.

Specific examples include but are not limited to compounds according to(b) wherein X is H, for example compounds with X being H and Rf being aC1 to C3 perfluoroalkylene. Particular examples include: bromo- oriodo-trifluoroethene,4-bromo-perfluorobutene-1,4-iodo-perfluorobutene-1, or bromo- oriodo-fluoroolefins such as 1-iodo,2,2-difluroroethene,1-bromo-2,2-difluoroethene, 4-iodo-3,3,4,4,-tetrafluorobutene-1 and4-bromo-3,3,4,4-tetrafluorobutene-1;6-iodo-3,3,4,4,5,5,6,6-octafluorohexene-1.

In some embodiments, the cure sites comprise chlorine atoms. Suchcure-site monomers include those of the general formula: CX₁X₂═CY₁Y₂where X₁, X₂ are independently H and F; Y₁ is H, F, or Cl; and Y₂ is Cl,a fluoroalkyl group (R_(F)) with at least one Cl substituent, afluoroether group (OR_(F)) with at least one Cl substituent, or—CF₂—OR_(F). The fluoroalkyl group (R_(F)) is typically a partially orfully fluorinated C₁-C₅ alkyl group. Examples of cure-site monomer withchlorine atoms include CF₂═CFCl, CF₂═CF—CF₂Cl, CF₂═CF—O—(CF₂)_(n)—Cl,n=1-4; CH₂=CHCl, CH₂=CCl₂.

Typically, the amount of iodine or bromine or chlorine or theircombination in the fluoropolymer is between 0.001 and 5/a, preferablybetween 0.01 and 2.5%, or 0.1 to 1% or 0.2 to 0.6% by weight withrespect to the total weight of the fluoropolymer. In one embodiment thecurable fluoropolymers contain between 0.001 and 5%, preferably between0.01 and 2.5%, or 0.1 to 1%, more preferably between 0.2 to 0.6% byweight of iodine based on the total weight of the fluoropolymer.

The composition may optionally further comprise a second fluoropolymerthat lacks halogen cure sites. The amount of fluoropolymer lackinghalogen cure sites is typically less than 50, 45, 40, 35, 30, 25, 20,15, 10, or 5 wt. % of the total fluoropolymer. Thus, the composition hasa sufficient amount of fluoropolymer with halogen cure sites such thatadequate crosslinking is achieved.

In one embodiments, the composition further comprises a secondfluoropolymer derived predominantly, or exclusively from two or moreperfluorinated comonomers including tetrafluoroethene (TFE) and one ormore unsaturated cyclic perfluorinated alkyl ethers, such as2,2-bistrifluoromethyl-4,5-difluoro-1,3 dioxole. Such fluoropolymers arecommercially available as “TEFLON™ AF”, “CYTOP™”, and “HYFLON™”.

In some embodiments, the second fluoropolymer containsnitrile-containing cure sites. When a combination of fluoropolymers withdifferent cure site is utilized the composition may be characterized asa dual curing, containing different cure sites that are reactive todifferent curing systems.

Although fluoropolymer with halogen cure sites (iodine, bromine, andchlorine) are favored for UV curing, in the case of thermal or e-beamcuring; fluoropolymers with nitrile-containing cure cites canalternatively be employed.

Fluoropolymers with nitrile-containing cure sites are known, such asdescribed in U.S. Pat. No. 6,720,360.

Nitrile-containing cure sites may be reactive to other cure systems forexample, but not limited to, bisphenol curing systems, peroxide curingsystems, triazine curing systems, and especially amine curing systems.Examples of nitrile containing cure site monomers correspond to thefollowing formulae:

CF₂=CF—CF₂—O—Rf-CN;

CF₂=CFO(CF₂)_(r)CN;

CF₂=CFO[CF₂CF(CF₃)O]_(p)(CF₂)_(v)OCF(CF₃)CN;

CF₂=CF[OCF₂CF(CF₃)]O(CF₂)_(u)CN;

wherein, r represents an integer of 2 to 12; p represents an integer of0 to 4; k represents 1 or 2; v represents an integer of 0 to 6; urepresents an integer of 1 to 6, Rf is a perfluoroalkylene or a bivalentperfluoroether group. Specific examples of nitrile containingfluorinated monomers include but are not limited to perfluoro(8-cyano-5-methyl-3,6-dioxa-1-octene), CF₂=CFO(CF₂)₅CN, andCF₂=CFO(CF₂)₃OCF(CF₃)CN.

In some embodiments, the amount of nitrile-containing cure sitecomonomer is typically at least 0.5, 1, 1.5, 2, 2.5, 3.3.5, 4, 4.5 or 5%by weight and typically no greater than 10% by weight; based on thetotal weight of the fluoropolymer. Suitable curing agents for nitrilecure sites are known in the art and include, but are not limited to(e.g. fluorinated) amidines, amidoximes and others described inWO2008/094758 A1, incorporated herein by reference. Representativecuring agents include for example bis-tetraphosphonium perfluoroadipate,methyl sulfone, tetrabutyl phosphonium toluy-hexafluoroisopropoxydetrifluoromethoxy, and tetrafluoropropyl amidine.

In one embodiment, the fluoropolymer with nitrile-containing cure sitescan be combined with a peroxide and ethylenically unsaturated compoundas curing agents as described in WO 2018/107017. In this embodiments,suitable organic peroxides are those which generate free radicals atcuring temperatures. Examples include dialkyl peroxides or bis(dialkylperoxides), for example. a di-tertiarybutyl peroxide having a tertiarycarbon atom attached to the peroxy oxygen. Specific examples include2,5-dimethyl-2,5-di(tertiarybutylperoxy)hexyne-3 and2,5-dimethyl-2,5-di(tertiarybutylperoxy)hexane; dicumyl peroxide,dibenzoyl peroxide, tertiarybutyl perbenzoate,alpha,alpha′-bis(t-butylperoxy-diisopropylbenzene), anddi[1,3-dimethyl-3-(t-butylperoxy)-butyl]carbonate. Generally, about 1 to5 parts of peroxide per 100 parts of fluoropolymer may be used.

In other embodiments, the composition is substantially free offluoropolymer with nitrile-containing cure sites. In this embodiment,the composition is also free of curing agents that react with nitrilegroups.

In other embodiments, halogenated chain transfer agents can be utilizedto provide terminal cure sites. Chain transfer agents are compoundscapable of reacting with the propagating polymer chain and terminatingthe chain propagation. Examples of chain transfer agents reported forthe production of fluoroelastomers include those having the formulaRI_(x), wherein R is an x-valent fluoroalkyl or fluoroalkylene radicalhaving from 1 to 12 carbon atoms, which, may be interrupted by one ormore ether oxygens and may also contain chlorine and/or bromine atoms. Rmay be Rf and Rf may be an x-valent (per)fluoroalkyl or(per)fluoroalkylene radical that may be interrupted once or more thanonce by an ether oxygen. Examples include alpha-omega diiodo alkanes,alpha-omega diiodo fluoroalkanes, and alpha-omegadiiodoperfluoroalkanes, which may contain one or more catenary etheroxygens. “Alpha-omega” denotes that the iodine atoms are at the terminalpositions of the molecules. Such compounds may be represented by thegeneral formula X—R—Y with X and Y being I and R being as describedabove. Specific examples include di-iodomethane, alpha-omega (or 1,4-)diiodobutane, alpha-omega (or 1,3-) diiodopropane, alpha-omega (or 1,5-)diiodopentane, alpha-omega (or 1,6-) diiodohexane and1,2-diiodoperfluoroethane.

Other examples include fluorinated di-iodo ether compounds of thefollowing formula:

R_(f)—CF(I)—(CX₂)_(n)—(CX₂CXR)_(m)—O—R″f-O_(k)—(CXR′CX₂)_(p)—(CX₂)_(q)—CF(I)—R′_(f)

wherein X is independently selected from F, H, and Cl; R_(f) and R′_(f)are independently selected from F and a monovalent perfluoroalkanehaving 1-3 carbons; R is F, or a partially fluorinated or perfluorinatedalkane comprising 1-3 carbons; R″_(f) is a divalent fluoroalkylenehaving 1-5 carbons or a divalent fluorinated alkylene ether having 1-8carbons and at least one ether linkage; k is 0 or 1; and n, m, and p areindependently selected from an integer from 0-5, wherein, n plus m atleast 1 and p plus q are at least 1.

The fluoropolymers may or may not contain units derived from at leastone modifying monomer. The modifying monomers may introduce branchingsites into the polymer architecture. Typically, the modifying monomersare bisolefins, bisolefinic ethers or polyethers. The bisolefins andbisolefinic (poly)ethers may be perfluorinated, partially fluorinated ornon-fluorinated. Preferably they are perfluorinated. Suitableperfluorinated bisolefinic ethers include those represented by thegeneral formula:

CF₂=CF—(CF₂)_(n)—O—(Rf)-O—(CF₂)_(m)—CF═CF₂

wherein n and m are independent from each other either 1 or 0 andwherein Rf represents a perfluorinated linear or branched, cyclic oracyclic aliphatic or aromatic hydrocarbon residue that may beinterrupted by one or more oxygen atoms and comprising up to 30 carbonatoms. A particular suitable perfluorinated bisolefinic ether is adi-vinylether represented by the formula:

CF₂=CF—O—(CF₂)_(n)—O—CF=CF₂

wherein n is an integer between 1 and 10, preferably 2 to 6, e.g. n maybe 1, 2, 3, 4, 5, 6 or 7. More preferably, n represents an uneveninteger, for example 1, 3, 5 or 7.

Further specific examples include bisolefinic ethers according thegeneral formula

CF₂=CF—(CF₂)_(n)—O—(CF₂)_(p)—O—(CF₂)_(m)—CF=CF₂

wherein n and m are independently either 1 or 0 and p is an integer from1 to 10 or 2 to 6. For example, n may be selected to represent 1, 2, 3,4, 5, 6 or 7, preferably, 1, 3, 5 or 7.

Further suitable perfluorinated bisolefinic ethers can be represented bythe formula

CF₂=CF—(CF₂)_(p)—O—(R_(af)O)_(n)(R_(bf)O)_(m)—(CF₂)_(q)—CF=CF₂

wherein R_(af) and R_(bf) are different linear or branchedperfluoroalkylene groups of 1-10 carbon atoms, in particular, 2 to 6carbon atoms, and which may or may not be interrupted by one or moreoxygen atoms. R_(af) and/or R_(bf) may also be perfluorinated phenyl orsubstituted phenyl groups; n is an integer between 1 and 10 and m is aninteger between 0 and 10, preferably m is 0. Further, p and q areindependently 1 or 0.

In another embodiment, the perfluorinated bisolefinic ethers can berepresented by the formula just described wherein m, n, and p are zeroand q is 1-4.

Modifying monomers can be prepared by methods known in the art and arecommercially available, for example, from Anles Ltd., St. Petersburg,Russia.

Preferably, the modifiers are not used or only used in low amounts.Typical amounts include from 0 to 5%, or from 0 to 1.4% by weight basedon the total weight of the fluoropolymer. Modifiers may be present, forexample, in amounts from about 0.1% to about 1.2% or from about 0.3% toabout 0.8% by weight based on the total weight of fluoropolymer.Combinations of modifiers may also be used.

The fluoropolymers may contain partially fluorinated or non-fluorinatedcomonomers and combinations thereof, although this is not preferred.Typical partially fluorinated comonomers include but are not limited to1,1-difluoroethene (vinylidenefluoride, VDF) and vinyl fluoride (VF) ortrifluorochloroethene or trichlorofluoroethene. Examples ofnon-fluorinated comonomers include but are not limited to ethene andpropene. The amount of units derived from these comonomers include from0 to 8% by weight based on the total weight of the fluoropolymer. Insome embodiments, the concentration of such comonomer is no greater than7, 6, 5, 4, 3, 2, or 1% by weight based on the total weight of thefluoropolymer.

In a preferred embodiment, the curable fluoropolymer is aperfluoroelastomer that comprises repeating units (exclusively) derivedfrom the perfluorinated comonomers but may contain units derived fromcure-site monomers and modifying monomers if desired. The cure-sitemonomers and modifying monomers may be partially fluorinated, notfluorinated or perfluorinated, and preferably are perfluorinated. Theperfluoroelastomers may contain from 69 to 73, 74, or 75% fluorine byweight (based on the total amount of perfluoroelastomer). The fluorinecontent may be achieved by selecting the comonomers and their amountsaccordingly.

Such highly-fluorinated amorphous fluoropolymers typically do notdissolve to the extent of at least 1 wt. %, at room temperature andstandard pressure, in a hydrogen-containing organic liquid (e.g., itdoes not dissolve in any of methyl ethyl ketone (“MEK”), tetrahydrofuran(“THF”), ethyl acetate or N-methyl pyrrolidinone (“NMP”)).

The fluoropolymers can be prepared by methods known in the art, such asbulk, suspension, solution or aqueous emulsion polymerization. Variousemulsifiers can be used as described in the art, including for example3H-perfluoro-3-1(3-methoxy-propoxy)propanoic acid. For example, thepolymerization process can be carried out by free radical polymerizationof the monomers alone or as solutions, emulsions, or dispersions in anorganic solvent or water. Seeded polymerizations may or may not be used.Curable fluoroelastomers that can be used also include commerciallyavailable fluoroelastomers, in particular perfluoroelastomers.

The fluoropolymers may have a monomodal or bi-modal or multi-modalweight distribution. The fluoropolymers may or may not have a core-shellstructure. Core-shell polymers are polymers where towards the end of thepolymerization, typically after at least 50% by mole of the comonomersare consumed, the comonomer composition or the ratio of the comonomersor the reaction speed is altered to create a shell of differentcomposition.

The fluorine content of the fluoropolymer is typically at least 60, 65,66, 67, 68, 69, or 70 wt. % of the fluoropolymer and typically nogreater than 76, 75, 74, or 73 wt. %.

The fluoropolymer compositions described herein contain one or moreethylenically unsaturated curing agents. The ethylenically unsaturatedcuring agents are typically present in an amount of at least 1, 1.5, or2 wt. % based on the total weight of the fluoropolymer. For compositionshaving a lower amount of crosslinking, the ethylenically unsaturatedcuring agents may be present at a lower amount such as at least 0.005,0.1, 0.2, 0.3, 0.5 wt. %. The maximum amount of ethylenicallyunsaturated curing agents is typically no greater than 10, 9, 8, 7, 6,or 5 wt. % based on the total weight of the fluoropolymer.

The ethylenically unsaturated group(s) of the curing agent are typically(meth)acryl including (meth)acrylate RCH═CHCOO— and (meth)acrylamideRCH═CHCONH—, wherein R is methyl of hydrogen; alkenyl including vinyl(CH₂═CH—); or alkynyl.

Useful multi-(meth)acrylate curing agents include

-   -   (a) di(meth)acryl containing monomers such as 1,3-butylene        glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol        diacrylate, 1,6-hexanediol monoacrylate monomethacrylate,        ethylene glycol diacrylate, alkoxylated aliphatic diacrylate,        alkoxylated cyclohexane dimethanol diacrylate, alkoxylated        hexanediol diacrylate, alkoxylated neopentyl glycol diacrylate,        caprolactone modified neopentylglycol hydroxypivalate        diacrylate, caprolactone modified neopentylglycol        hydroxypivalate diacrylate, cyclohexanedimethanol diacrylate,        diethylene glycol diacrylate, dipropylene glycol diacrylate,        ethoxylated bisphenol A diacrylate, hydroxypivalaldehyde        modified trimethylolpropane diacrylate, neopentyl glycol        diacrylate, polyethylene glycol diacrylate, propoxylated        neopentyl glycol diacrylate, tetraethylene glycol diacrylate,        tricyclodecanedimethanol diacrylate, triethylene glycol        diacrylate, tripropylene glycol diacrylate;    -   (b) tri(meth)acryl containing monomers such as glycerol        triacrylate, trimethylolpropane triacrylate, ethoxylated        triacrylates (e.g., ethoxylated trimethylolpropane triacrylate),        propoxylated triacrylates (e.g., propoxylated glyceryl        triacrylate, propoxylated trimethylolpropane triacrylate),        trimethylolpropane triacrylate, tris(2-hydroxyethyl)isocyanurate        triacrylate;    -   (c) higher functionality (meth)acryl containing monomer such as        ditrimethylolpropane tetraacrylate, dipentaerythritol        pentaacrylate, pentaerythritol triacrylate, ethoxylated        pentaerythritol tetraacrylate, and caprolactone modified        dipentaerythritol hexaacrylate.

In some embodiments, the ethylenically unsaturated curing agentcomprises at least two or three ethylenically unsaturated groups. Themaximum number of ethylenically unsaturated groups is typically 3, 4, 5,or 6. In this embodiment, the ethylenically unsaturated groups arepreferably alkenyl groups. Thus, the composition in some embodiments,the composition is substantially free of (meth)acrylate groups.

The ethylenically unsaturated curing agent may be linear, branched, orcomprise a cyclic group. The ethylenically unsaturated curing agent maybe aliphatic or aromatic. Examples of useful ethylenically unsaturatedcuring agents include triallyl cyanurate; triallyl isocyanurate;triallyl trimellitate; tri(methylallyl)isocyanurate;tris(diallylamine)-s-triazine; triallyl phosphite; (N,N′)-diallylacrylamide; hexaallyl phosphoramide; (N,N,N,N)-tetraalkyltetraphthalamide; (N,N,N′,N-tetraallylmalonamide; trivinyl isocyanurate;N,N′-m-phenylenebismaleimide; diallyl-phthalate andtri(5-norbomene-2-methylene)cyanurate. In some embodiments, theethylenically unsaturated curing agent is heterocyclic such as in thecase of triallyl isocyanurate (TAIC).

In some embodiments, the ethylenically unsaturated curing agentcomprises a silicone-containing moiety such as silane or siloxane. Whenthe curing agent includes silicone-containing moiety, the curing agentcan also promote adhesion of the fluoropolymer to a substrate.

Suitable ethylenically unsaturated curing agent that comprisesilicone-containing moieties include for example diallydimethylsilane;and 1,3-divinyltetramethyl disiloxane.

In some embodiment, the ethylenically unsaturated curing agent comprisesat least one ethylenically unsaturated group and at least one alkoxysilane group. Suitable curing agents include for example (meth)acryloyalkoxy silanes such as 3-(methacryloxy)propyltrimethoxysilane,3-(methacryloxy)propylmethyldimethoxysilane, 3-(acryloyloxypropyl)methyldimethoxysilane, 3-(methacryloyloxy)propyldimethylmethoxysilane, and3-(acryloxypropyl) dimethylmethoxysilane. In some embodiments, theamount of (meth)acryloy alkoxy silanes is at least 2, 3, 4, or 5 wt. %to achieve a highly crosslinked fluoropolymer.

Suitable alkenyl alkoxy silanes include vinyldimethylethoxysilane,vinylmethyldiacetoxysilane, vinylmethyldiethoxysilane,vinyltriacetoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane,vinyltrimethoxysilane, vinyltriphenoxysilane, vinyltri-t-butoxysilane,vinyltris-isobutoxysilane, vinyltriisopropenoxysilane,vinyltris(2-methoxyethoxy)silane, and allyltriethoxysilane.

In some embodiments, the ethylenically unsaturated curing agent may havethe general formula

X¹-L¹-SiR_(m)(OR¹)_(3-m);

-   -   wherein X¹ is an ethylenically unsaturated group, such as        (meth)acryl or vinyl;    -   L¹ is an organic divalent linking group having 1 to 12 carbon        atoms;    -   R is independently C₁-C₄ alkyl and most typically methyl or        ethyl;    -   R¹ is independently H or C₁-C₄ alkyl and most typically methyl        or ethyl; and    -   m ranges from 0 to 2.

In typical embodiments, L¹ is an alkylene group. In some embodiments, L¹is an alkylene group having 1, 2 or 3 carbon atoms. In otherembodiments, L¹ comprises or consists of an aromatic group such asphenyl or (e.g. C₁-C₄) alkyl phenyl.

The composition may comprise a single ethylenically unsaturated curingagent as just described or combinations of ethylenically unsaturatedcuring agents.

The composition described herein further comprises an electron donorgroup or precursor thereof. The electron donor group may be present onthe same compound such as in the case of an aminoalkene or vinylanilineor the electron donor group may be present as a separate compound.

The fluoropolymer and/or the curing agent(s) comprise a chromophore,i.e. an atom or group that absorbs light at a specified frequency. Insome embodiments, the fluororpolymer and/or curing agent may not havesufficient absorbance independently, but have sufficient absorbance incombination with each other.

In some embodiments, the fluoropolymer, curing agent(s), or combination,thereof have an absorbance of at least 0.1, 0.2, 0.3, 0.4, 0.5, 0.6,0.7, 0.8, 0.9, or 1.0 at wavelength ranging from 190 nm to 400 nm. Insome embodiments, such absorbance is at wavelength of at least 200 nm,210 nm, 220 nm, 230 nm or 240 nm. In some embodiments, such absorbanceis at wavelength of no greater than 350, 340, 330, 320, 310 nm, or 290nm. In other embodiments, the fluoropolymer, curing agent(s), orcombination, thereof have an absorbance of at least 0.1, 0.2, 0.3, 0.4,0.5, 0.6, 0.7, 0.8, 0.9, or 1.0 at wavelength ranging from 150 nm to 200nm.

Without intending to be bound by theory, it is surmised that uponexposure to suitable wavelengths and intensities of actinic (e.g. UV)radiation the halogen atoms of the cure sites of the fluoropolymerbecome excited and ionize. The ionized halogen atoms react with theelectron donor group rendering protonated cure sites in place of theformer halogen atoms. Such protonated cure site covalently bond with theethylenically unsaturated group(s) of the curing agent.

Although other electron donor groups could be utilized, the compoundcomprising an electron donor group is typically an amine, or precursorthereof. Suitable amines include primary amine, secondary amines,tertiary amines, and combinations thereof. The amine may be aliphatic oraromatic. Amine compounds can also be utilized to provide a crosslinkedfluoropolymer layer by (e.g. thermally) curing a fluoropolymer with(e.g. nitrile) cure sites utilizing an amine cuing agent.

Illustrative amine compounds include diamino hexane,N,N,N′,N′-tetramethyl-1,4-diamino butane (TMDAB); N,N-dimethyl aniline;triethylenetetramine; and diethylenetriamine. In some embodiments, theamine groups are spaced apart by an alkylene group having at least 3, 4,5, or 6 (e.g. carbons) atoms. Typically, the number of (e.g. carbon)atoms is no greater than 12. When the amine compound has an insufficientchain length, it can be a less effective electron donor group. Thealkylene group can optionally comprise substituents, such as siloxane,provided the compound is an electron donor or precursor thereof.

In some embodiments, the electron donor compound may be characterized asan electron donor precursor meaning that when the compound is initiallycombined with the fluoropolymer it is not an electron donor. However,the precursor compound decomposes or otherwise reacts to form an (e.g.amine) electron donor prior to or during curing.

Electron donor precursors include nitrogen-containing nucleophiliccompounds such as heterocyclic secondary amines; guanidines; compoundswhich decompose in-situ at a temperature between 40° C. and 330° C. toproduce a guanidine; compounds which decompose in-situ at a temperaturebetween 40° C. and 330° C. to produce a primary or secondary amine;nucleophilic compounds of the formula R₁—NH—R₂, wherein R₁ is H-, aC₁-C₁₀ aliphatic hydrocarbon group, or an aryl group having hydrogenatoms in the alpha positions. R₂ is a C₁-C₁₀ aliphatic hydrocarbongroup, an aryl group having hydrogen atoms in the alpha positions,—CONHR₃, —NHCO₂R₃, or —OH′, and R₃ is a C₁-C₁₀ aliphatic hydrocarbongroup; and substituted amidines of the formula HN═CR₄NR₅R₆, wherein R₄,R₅, R₆ are independently H-, alkyl or aryl groups and wherein at leastone of R₄, R₅ and Re is not H—.

As used herein. “heterocyclic secondary amine” refers to aromatic oraliphatic cyclic compound having at least one secondary amine nitrogencontained within the ring. Such compounds include, for example, pyrrole,imidazole, pyrazole, 3-pyrroline, and pyrrolidine.

Guanidines are compounds derived from guanidine, i.e. compounds whichcontain the radical, —NHCNHNH—, such as, but not limited to.diphenylguanidine, diphenylguanidine acetate, aminobutylguanidine,biguanidine, isopentylguanidine, di-σ-tolylguanidine, o-tolylbiguanide,and triphenylguanidine.

Other compounds that decompose in-situ at a temperature between 40° C.and 330° C. to produce either a primary or secondary amine include, butare not limited to, di- or poly-substituted ureas (e.g. 1,3-dimethylurea); N-alkyl or -dialkyl carbamates (e.g.N-(tert-butyloxycarbonyl)propylamine); di- or poly-substituted thioureas(e.g. 1,3-dimethyl-thiourea); aldehyde-amine condensation products (e.g.1,3,5-trimethylhexahydro-1,3,5-triazine); N,N′-dialkyl phthalamidederivatives (e.g. N,N′-dimethylphthalamide); and amino acids.

When thermally activated electron donor precursor compounds are utilizedas just described, the composition is typically heated prior to and/orduring curing.

Other types of amine electron donor include bis(aminophenols) andbis(aminothiophenols) of the formulas

-   -   and tetraamines of the formula

where A is SO₂, O, CO, alkyl of 1-6 carbon atoms, perfluoroalkyl of 1-10carbon atoms, or a carbon-carbon bond linking the two aromatic rings.The amino and hydroxyl groups in the above formulas are interchangeablyin the meta and para positions with respect to group A.

In some embodiments, the amine electron donor compound is an aziridinecompound. In some embodiments, the aziridine compound comprises at leasttwo aziridine groups. The aziridine compound may comprise 3, 4, 5, 6, orgreater than 6 aziridine groups. The aziridine compound may berepresented by the following structure:

-   -   wherein R is a core moiety having a valency of Y;    -   L is a bond, divalent atom, or divalent linking group;    -   R₁, R₂, R₃, and R₄ are independently hydrogen or a C₁-C₄ alkyl        (e.g. methyl); and    -   Y is typically 2, 3, or greater.

In some embodiments, R is —SO₂—. In some embodiments, R-L is a residueof a multi(meth)acrylate compound. In some embodiments L is a C₁-C₄alkylene, optionally substituted with one or more (e.g. contiguous orpendant) oxygen atoms thereby forming ether or ester linkages. Intypical embodiments, R₁ is methyl and R₂, R₃, and R₄ are hydrogen.

Representative aziridine compounds include trimethylolpropanetri-[beta-(N-aziridinyl)-propionate, 2,2-bishydroxymethylbutanoltris[3-(1-aziridine) propionate];1-(aziridin-2-yl)-2-oxabut-3-ene; and 4-(aziridin-2-yl)-but-1-ene; and5-(aziridin-2-yl)-pent-1-ene.

In some embodiments, a polyaziridine compound can be prepared byreacting divinyl sulfone with alkylene (e.g. ethylene) imine, such asdescribed in U.S. Pat. No. 3,235,544 (Christena). On representativecompound is di(2-propyleniminoethyl)sulfone, as depicted as follows:

The above described polyaziridine compounds comprise at least twoaziridine groups at the time the compound is added to the coatingcomposition. In other embodiments, the polyaziridine compound does notcomprise two aziridine groups at the time the compound is added to thecomposition, yet forms a polyaziridine in-situ. For example, compoundscomprising a single aziridine group and a single (meth)acrylate groupcan form a dimer or oligomerize by reaction of the (meth)acrylate groupsthereby forming a polyaziridine (i.e. diaziridine) compound.

In some embodiments, the composition comprises an electron donorcompound comprising at least one (e.g. primary, secondary tertiary)amine group and at least one organosilane (e.g. alkoxy silane) group.Such compounds can improve bonding an independently crosslink thefluoroelastomers described herein, thereby providing a secondfluoropolymer crosslinking mechanism. By use of ethylenicallyunsaturated curing agents in combination with amino-substitutedorganosilanes, highly crosslinked fluoropolymers can be providedutilizing lower concentrations of curing agents and electron donorcompounds.

In some embodiments, the amine may be characterized as anamino-substituted organosilane ester or ester equivalent that bear onthe silicon atom at least one, and preferably 2 or 3 ester or esterequivalent groups. Ester equivalents are known to those skilled in theart and include compounds such as silane amides (RNR′Si), silanealkanoates (RC(O)OSi), Si—O—Si, SiN(R)—Si, SiSR and RCONR′Si compoundsthat are thermally and/or catalytically displaceable by R″OH. R and R′are independently chosen and can include hydrogen, alkyl, arylalkyl,alkenyl, alkynyl, cycloalkyl, and substituted analogs such asalkoxyalkyl, aminoalkyl, and alkylaminoalkyl. R″ may be the same as Rand R′, except it may not be H. These ester equivalents may also becyclic such as those derived from ethylene glycol, ethanolamine,ethylenediamine (e.g. N-[3-(trimethoxylsilyl)propyl] ethylenediamine)and their amides.

Another such cyclic example of an ester equivalent is

In this cyclic example R′ is as defined in the preceding sentence,except that it may not be aryl. 3-aminopropyl alkoxysilanes are wellknown to cyclize upon heating, and these RNHSi compounds would be usefulin this invention. Preferably the amino-substituted organosilane esteror ester equivalent has ester groups such as methoxy that are easilyvolatilized as methanol. The amino-substituted organosilane must have atleast one ester equivalent; for example, it may be a trialkoxysilane.

For example, the amino-substituted organosilane may have the formula

(Z₂N-L-SiX′X″X′″), wherein

Z is hydrogen, alkyl, or substituted aryl or alkyl includingamino-substituted alkyl; and L is a divalent straight chain C1-12alkylene or may comprise a C3-8 cycloalkylene, 3-8 membered ringheterocycloalkylene, C2-12 alkenylene, C4-8 cycloalkenylene, 3-8membered ring heterocycloalkenylene or heteroarylene unit; and each ofX′, X″ and X′″ is a C1-18 alkyl, halogen, C1-8 alkoxy, C1-8alkylcarbonyloxy, or amino group, with the proviso that at least one ofX′, X″, and X′″ is a labile group. Further, any two or all of X′, X″ andX′ may be joined through a covalent bond. The amino group may be analkylamino group.

L may be divalent aromatic or may be interrupted by one or more divalentaromatic groups or heteroatomic groups. The aromatic group may include aheteroaromatic. The heteroatom is preferably nitrogen, sulfur or oxygen.L is optionally substituted with C1-4 alkyl, C2-4 alkenyl, C2-4 alkynyl,C1-4 alkoxy, amino, C3-6 cycloalkyl, 3-6 membered heterocycloalkyl,monocyclic aryl, 5-6 membered ring heteroaryl, C1-4 alkylcarbonyloxy,C1-4 alkyloxycarbonyl, C1-4 alkylcarbonyl, formyl, C1-4alkylcarbonylamino, or C1-4 aminocarbonyl. L is further optionallyinterrupted by —O—, —S—, —N(Rc)-, —N(Rc)-C(O)—, —N(Rc)-C(O)—O—,—O—C(O)—N(Rc)-, —N(Rc)-C(O)—N(Rd)-, —O—C(O)—, —C(O)—O—, or —O—C(O)—O—.Each of Rc and Rd, independently, is hydrogen, alkyl, alkenyl, alkynyl,alkoxyalkyl, aminoalkyl (primary, secondary or tertiary), or haloalkyl.

Examples of amino-substituted organosilanes include3-aminopropyltrimethoxysilane (SILQUEST A-1110),3-aminopropyltriethoxysilane (SILQUEST A-1100),bis(3-trimethoxysilylpropy)amine, bis(3-triethoxysilylpropy)amine,bis(3-trimethoxysilylpropy)n-methylamine,3-(2-aminoethyl)aminopropyltrimethoxysilane (SILQUEST A-1120), SILQUESTA-1130, (aminoethylaminomethyl)phenethyltrimethoxysilane,(aminoethylaminomethyl)-phenethyltriethoxysilane,N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane (SILQUEST A-2120),bis-(.gamma.-triethoxysilylpropyl)amine (SILQUEST A-1170),N-(2-aminoethyl)-3-aminopropyltributoxysilane,6-(aminohexylaminopropyl)trimethoxysilane, 4-aminobutyltrimethoxysilane,4-aminobutyltriethoxysilane, p-(2-aminoethyl)phenyltrimethoxysilane,3-aminopropyltris(methoxyethoxyethoxy)silane,3-aminopropylmethyldiethoxy-silane, oligomeric aminosilanes such asDYNASYLAN 1146, 3-(N-methylamino)propyltrimethoxysilane,N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane,N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,N-(2-aminoethyl)-3-aminopropyltriethoxysilane,3-aminopropylmethyldiethoxysilane, 3-aminopropylmethyldimethoxysilane,3-aminopropyldimethylmethoxysilane, 3-aminopropyldimethylethoxysilane,and the following cyclic compounds:

A bis-silyl urea [RO)₃Si(CH₂)NR]₂C═O is another example of anamino-substituted organosilane ester or ester equivalent.

In some embodiments, the curing agent may comprise an amino group havinglatent functionality. One example of such curing agent is a blockedamine group, such as

R³—N═C(R¹)(R²)

wherein R¹ and R² are independently selected from a linear or branchedalkyl group comprising 1 to 6 carbon atoms. In typical embodiments R1 ismethyl, and R² a linear or branched alkyl group comprising at least 2,3, 4, 5, or 6 carbon atoms. R³ is typically an organic group (e.g.having a molecular weight less than 500, 450, 400, 350, 300, or 250g/mole).

The blocked amine can be activated by moisture provided by wateradsorbed on the surface of the substrate being coated or from humidity.Deblocking begins in minutes and is generally complete within a few(e.g. two) hours. During deblocking the —N═C(R¹)(R²) group is convertedto —NH₂ that can then react with the (e.g. nitrile cure sites) of thefluoropolymer.

In some embodiments, the curing agent comprises a blocked amine groupand an alkoxy silane group. Such blocked amine curing agent can becharacterized by the following general formula:

(R⁴O)₃—Si—(CH₂)_(m)—N═C(R1)(R2)

wherein R¹ and R² are independently selected from a linear or branchedalkyl group comprising 1 to 6 carbon atoms as previously described. R¹is independently selected from a linear or branched alkyl groupcomprising 1 to 6 carbon atoms, m is an integer from 1 to 4, and each R⁴is independently a C1 or C2 alkyl group.

One illustrative curing agent comprising a blocked amine group and analkoxy silane group isN-(1,3-dimethylbutylidene)aminopropyl-triethoxysilane, depicted asfollows:

Such curing agent is available from Gelest and from 3M as “3M™ Dynamer™Rubber Curative RC5125”. Blocked amines are additional examples ofelectron donor precursors.

In some embodiments, the amine curing agent comprises an aziridine groupand an alkoxy silane group. Such compounds are known for examples fromU.S. Pat. No. 3,243,429; incorporated herein by reference. Aziridinealkoxy silane compounds may have the general structure:

-   -   wherein R″ is hydrogen or a C₁-C₄ alkyl (e.g. methyl);    -   X is a bond, a divalent atom, or a divalent linking group;    -   n is 0, 1 or 2;    -   m is 1, 2, or 3; and    -   and the sum or n+m is 3.

One representative compound is 3-(2-methylaziridinyl)ethylcarboxylpropyltriethoxysilane.

Various other suitable aziridine crosslinkers are known, such asdescribed in WO2014/075246; published May 22, 2014, incorporated hereinby reference; and “NEW GENERATION OF MULTIFUNCTIONAL CROSSLINKERS,” (Seehttps://www.pstc.org/files/public/Milker00.pdf).

The composition comprises a single (e.g. amine) electron donor compoundor a combination of amine electron donor compounds may be present.

The amount of (e.g. amine) electron donor compound is typically at least0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3,0.4, or 0.5% by weight solids (i.e. excluding the solvent of the coatingcomposition). In some embodiments, the amount of (e.g. amine) electrondonor compound is no greater than 5, 4.5, 4, 3.5, or 3% by weightsolids.

In some embodiments, the fluoropolymer composition further comprises analkoxy silane compound that lacks amine functionality. In someembodiments, such alkoxy silanes may be characterized as“non-functional” having the chemical formula:

R²Si(OR¹)_(m)

-   -   wherein R¹ is independently alkyl as previously described;    -   R² is independently hydrogen, alkyl, aryl, alkaryl, or OR¹; and    -   m ranges from 1 to 3, and is typically 2 or 3 as previously        described.

Suitable alkoxy silanes of the formula R²Si(OR¹)_(m) include, but arenot limited to tetra-, tri- or dialkoxy silanes, and any combinations ormixtures thereof. Representative alkoxy silanes includepropyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane,butyltriethoxysilane, pentyltrimethoxysilane, pentyltriethoxysilane,heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane,octyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane,hexadecyltrimethoxysilane, hexadecyltriethoxysilane,octadecyltrimethoxysilane, octadecyltriethoxysilane,phenyltrimethoxysilane, phenyltriethoxysilane dimethyldimethoxysilaneand dimethyldiethoxysilane.

Preferably, the alkyl group(s) of the alkoxy silanes comprises from 1 to6, more preferably 1 to 4 carbon atoms. Preferred alkoxysilanes for useherein are selected from the group consisting of tetra methoxysilane,tetra ethoxysilane, methyl triethoxysilane, dimethyldiethoxysilane, andany mixtures thereof. A preferred alkoxysilane for use herein comprisestetraethoxysilane (TEOS). The alkoxy silane lacking organofunctionalgroups utilized in the method of making the coating composition may bepartially hydrolyzed, such as in the case of partially hydrolyzedtetramethoxysilane (TMOS) available from Mitsubishi Chemical Companyunder the trade designation “MS-51”.

When present, the amount of alkoxy silane compound that lacks(amine/electron donor) functionality (e.g. TESO) is typically at least0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3,0.4, or 0.5% by weight solids (i.e. excluding the solvent of the coatingcomposition). In some embodiments, the amount of alkoxy silane compoundthat lacks functionality is no greater than 5, 4.5, 4, 3.5, or 3% byweight solids.

In some embodiments, the composition described herein comprise a (e.g.UV) curing system comprising an ethylenically unsaturated compound incombination with an electron donor compound, such as an amine, in theabsence of an organic peroxide. Organic peroxides are electron acceptorsand thus would compete with the ionized halogen atom, thereby reducingcrosslinking of the fluoropolymer. In some embodiments, the compositionis also substantially free of other electron acceptors that would reducecrosslinking.

In other embodiments, an amino organosilane ester compound or esterequivalent can be utilized in the absence of an ethylenicallyunsaturated compound can be utilized to (e.g. UV) cure and/or thermallycure the fluoropolymer, as described in PCT/US2019/036460, incorporatedherein by reference.

The fluoropolymer (coating solution) compositions comprises at least onesolvent. The solvent is capable of dissolving the fluoropolymer. Thesolvent is typically present in an amount of at least 25% by weightbased on the total weight of the coating solution composition. In someembodiments, the solvent is present in an amount of at least 30, 35, 40,45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95% or greater based on thetotal weight of the coating solution composition.

The fluoropolymer (coating solution) composition typically comprises atleast 0.01, 0.02, 0.03, 0.03, 0.04, 0.04, 0.05, 0.06, 0.7, 0.8, 0.9 or1% by weight of fluoropolymer, based on the weight of the total coatingsolution composition. In some embodiments, the fluoropolymer coatingsolution composition comprises at least 2, 3, 4, or 5% by weight offluoropolymer. In some embodiments, the fluoropolymer coating solutioncomposition comprises at least 6, 7, 8, 9 or 10% by weight offluoropolymer. The fluoropolymer coating solution composition typicallycomprises no greater than 50, 45, 40, 35, 30, 25, or 20% by weight offluoropolymer, based on the weight of the total coating solutioncomposition.

Optimum amounts of solvent and fluoropolymers may depend on the finalapplication and may vary. For example, to provide thin coatings, verydilute solutions of fluoropolymer in the solvent may be desired, forexample amounts of from 0.01% by weight to 5% by weight offluoropolymer. Also for application by spray coating composition of lowviscosity may be preferred over solutions with high viscosity. Theconcentration of fluoropolymer in the solution affects the viscosity andmay be adjusted accordingly. An advantage of the present disclosure isthat also solutions with high concentrations of fluoropolymer can beprepared that still provide clear liquid composition of low viscosity.

In some embodiments, the fluoropolymer coating solution compositions maybe liquids. The liquids may have, for example, a viscosity of less than2,000 mPas at room temperature (20° C.+/−2° C.). In other embodiments,the fluoropolymer coating solution compositions are pastes. The pastesmay have, for example, a viscosity of from 2,000 to 100.000 mPas at roomtemperature (20° C.+/−2° C.).

The solvent is a liquid at ambient conditions and typically has aboiling point of greater than 50° C. Preferably, the solvent has aboiling point below 200° C. so that it can be easily removed. In someembodiments, the solvent has a boiling point below 190, 180, 170, 160,150, 140, 130, 120, 110, or 100° C.

The solvent is partially fluorinated or perfluorinated. Thus, thesolvent is non-aqueous. Various partially fluorinated or perfluorinatedsolvents are known including perfluorocarbons (PFCs),hydrochlorofluorocarbons (HCFCs), perfluoropolyethers (PFPEs), andhydrofluorocarbons (HFCs), as well as fluorinated ketones andfluorinated alkyl amines.

In some embodiments, the solvent has a global warming potential (GWP,100 year ITH) of less than 1000, 900, 800, 700, 600, 500, 400, 300, 200or 100. The GWP is typically greater than 0 and may be at least 10, 20,30, 40, 50, 60, 70, or 80.

As used herein, GWP is a relative measure of the global warmingpotential of a compound based on the structure of the compound. The GWPof a compound, as defined by the Intergovernmental Panel on ClimateChange (IPCC) in 1990 and updated in subsequent reports, is calculatedas the warming due to the release of 1 kilogram of a compound relativeto the warming due to the release of 1 kilogram of CO₂ over a specifiedintegration time horizon (ITH).

${GWP_{x}} = \frac{\underset{0}{\int\limits^{ITH}}{\text{?}{\exp( {{- t}/\tau_{x}} )}{dt}}}{\underset{0}{\int\limits^{ITH}}{F_{{CO}_{2}}{C_{{CO}_{2}}(t)}{dt}}}$?indicates text missing or illegible when filed

where F is the radiative forcing per unit mass of a compound (the changein the flux of radiation through the atmosphere due to the IR absorbanceof that compound), C_(o) is the atmospheric concentration of a compoundat initial time, r is the atmospheric lifetime of a compound, t is time,and x is the compound of interest.

In some embodiments, the solvent comprises a partially fluorinated etheror a partially fluorinated polyether. The partially fluorinated ether orpolyether may be linear, cyclic or branched. Preferably, it is branched.Preferably it comprises a non-fluorinated alkyl group and aperfluorinated alkyl group and more preferably, the perfluorinated alkylgroup is branched.

In one embodiment, the partially fluorinated ether or polyether solventcorresponds to the formula:

Rf—O—R

wherein Rf is a perfluorinated or partially fluorinated alkyl or(poly)ether group and R is a non-fluorinated or partially fluorinatedalkyl group. Typically, Rf may have from 1 to 12 carbon atoms. Rf may bea primary, secondary or tertiary fluorinated or perfluorinated alkylresidue. This means, when Rf is a primary alkyl residue the carbon atomlinked to the ether atoms contains two fluorine atoms and is bonded toanother carbon atom of the fluorinated or perfluorinated alkyl chain. Insuch case Rf would correspond to R_(f) ¹—CF₂— and the polyether can bedescribed by the general formula: R_(f) ¹—CF₂—O—R.

When Rf is a secondary alkyl residue, the carbon atom linked to theether atom is also linked to one fluorine atoms and to two carbon atomsof partially and/or perfluorinated alkyl chains and Rf corresponds to(R_(f) ²R_(f) ³)CF₂—. The polyether would correspond to (R_(f) ²R_(f)³)CF—O—R.

When Rf is a tertiary alkyl residue the carbon atom linked to the etheratom is also linked to three carbon atoms of three partially and/orperfluorinated alkyl chains and Rf corresponds to (R_(f) ⁴R_(f) ⁵R_(f)⁶)—C—. The polyether then corresponds to (R_(f) ⁴R_(f) ⁵R_(f) ⁶)—C—OR.R_(f) ¹; R_(f) ²; R_(f) ³; R_(f) ⁴; R_(f) ⁵; R_(f) ⁶ correspond to thedefinition of Rf and are a perfluorinated or partially fluorinated alkylgroup that may be interrupted once or more than once by an ether oxygen.They may be linear or branched or cyclic. Also a combination ofpolyethers may be used and also a combination of primary, secondaryand/or tertiary alkyl residues may be used.

An example of a solvent comprising a partially fluorinated alkyl groupincludes C₃F₇OCHFCF₃ (CAS No. 3330-15-2).

An example of a solvent wherein Rf comprises a perfluorinated(poly)ether is C₃F₇OCF(CF₃)CF₂OCHFCF₃ (CAS No. 3330-14-1).

In some embodiments, the partially fluorinated ether solvent correspondsto the formula:

CpF2p+1-O—CqH2q+1

wherein q is an integer from 1 to and 5, for example 1, 2, 3, 4 or 5,and p is an integer from 5 to 11, for example 5, 6, 7, 8, 9, 10 or 11.Preferably, C_(p)F_(2p+1) is branched. Preferably, C_(p)F_(2p+1) isbranched and q is 1, 2 or 3.

Representative solvents include for example1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane and3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluroro-2-(trifluoromethyl)hexane.Such solvents are commercially available, for example, under the tradedesignation NOVEC from 3M Company, St. Paul, MN.

The fluorinated (e.g. ethers and polyethers) solvents may be used aloneor in combination with other solvents, which may be fluorochemicalsolvents or non-fluorochemical solvents. When a non-fluorochemicalsolvent is combined with a fluorinated solvent, the concentrationnon-fluorochemical solvent is typically less than 30, 25, 20, 15, 10 or5 wt-% with respect to the total amount of solvent. Representativenon-fluorochemical solvents include ketones such as acetone, MEK, methylisobutyl ketone, methyl amyl ketone and NMP; ethers such astetrahydrofuran, 2-methyl tetrahydrofuran and methyl tetrahydrofurfurylether; esters such as methyl acetate, ethyl acetate and butyl acetate;cyclic esters such as delta-valerolactone and gamma-valerolactone.

In some embodiments, the composition further comprises crystallinefluoropolymer particles.

In one embodiment, such coating composition is prepared by blending alatex containing crystalline fluoropolymer particles with a latexcontaining amorphous fluoropolymer particles. The fluoropolymerparticles typically have a small average particle diameter, for exampleless than 400 nm, but may be larger if especially when the appliedcoating will be rubbed after cure. For example, the fluoropolymerparticle size range may be about 50 to about 1000 nm, or about 50 toabout 400 nm, or about 50 to about 200 nm.

The latexes can be combined by any suitable manner such as by vortexmixing for 1-2 minutes. The method further comprises coagulating themixture of latex particles. Coagulation may be carried out, for example,by chilling (e.g., freezing) the blended latexes or by adding a suitablesalt (e.g., magnesium chloride). Chilling is especially desirable forcoatings that will be used in semiconductor manufacturing and otherapplications where the introduction of salts may be undesirable. Themethod further comprising optionally washing the coagulated mixture ofamorphous fluoropolymer particles and crystalline fluoropolymerparticles. The washing step may substantially remove emulsifiers orother surfactants from the mixture and can assist in obtaining awell-mixed blend of substantially unagglomerated dry particles. In someembodiments, the surfactant level of the resulting dry particle mixturemay, for example, be less than 0.1% by weight, less than 0.05% by weightor less than 0.01% by weight. The method further comprises drying thecoagulated latex mixture. The coagulated latex mixture can be dried byany suitable means such as air drying or oven drying. In one embodiment,the coagulated latex mixture can be dried at 100° C. for 1-2 hours.

The dried coagulated latex mixture can be dissolved in a solventsuitable for dissolving the amorphous fluoropolymer particles to form astable coating composition containing a homogeneous dispersion of thecrystalline fluoropolymer particles in a solution of the amorphousfluoropolymer.

The coating solution can be utilized to provide a coating on a substrateby applying a layer of the coating composition to a surface of asubstrates and drying (i.e. removing the fluorinated solvent byevaporation) the coating composition.

In some embodiments, the method further comprises rubbing (e.g. buffing,polishing) the dried layer thereby forming an amorphous fluoropolymerbinder layer containing crystalline submicron fluoropolymer particles.

The submicron crystalline fluoropolymer particles at the coating surfaceforms a thin, continuous or nearly continuous fluoropolymer surfacelayer disposed on the underlying coating comprised of the amorphousfluoropolymer. In preferred embodiments the thin crystallinefluoropolymer layer is relatively uniformly smeared over the underlyingcoating and appears to be thinner and more uniform than might be thecase if the fluoropolymer particles had merely undergone fibrillation(e.g., due to orientation or other stretching).

Average roughness (Ra) of the surface is the arithmetic average of theabsolute values of the surface height deviation measured from the meanplane In some embodiments, Ra is at least 40 or 50 nm, ranging up to 100nm before rubbing. In some embodiments, the surface after rubbing is atleast 10, 20, 30, 40, 50 or 60% smoother. In some embodiments, Ra isless than 35, 30, 25, or 20 nm after rubbing.

A variety of rubbing techniques can be employed at the time of coatingformation or later when the coated article is used or about to be used.Simply wiping or buffing the coating a few times using a cheesecloth orother suitable woven, nonwoven or knit fabric will often suffice to formthe desired thin layer. Those skilled in the art will appreciate thatmany other rubbing techniques may be employed. Rubbing can also reducehaze in the cured coating.

A variety of crystalline fluoropolymer particles may be employedincluding mixtures of different crystalline fluoropolymer particles. Thecrystalline fluoropolymer particles typically have high crystallinityand therefore a significant melting point (peak maximum) as determinedby differential scanning calorimetry in accordance with DIN EN ISO11357-3:2013-04 under nitrogen flow and a heating rate of 10° C./min.

For example, the crystalline fluoropolymer particles may includeparticles of fluoropolymers having a Tm of at least 100, 110, 120, or130° C. In some embodiments, the crystalline fluoropolymer particles mayinclude particles of fluoropolymers having a Tm no greater than 350,340, 330, 320, 310 or 300° C.

The crystalline fluoropolymer particles typically have a fluorinecontent greater than about 50 weight percent. Also, the fluoropolymerparticles may include particles of fluoropolymers having a fluorinecontent between about 50 and about 76 weight percent, between about 60and about 76 weight percent, or between about 65 and about 76 weightpercent.

Representative crystalline fluoropolymers include, for example,perfluorinated fluoropolymers such as 3M™ Dyneon™ PTFE Dispersions TF5032Z, TF 5033Z, TF 5035Z, TF 5050Z, TF 5135GZ, and TF 5070GZ; and 3M™Dyneon™ Fluorothermoplastic Dispersions PFA 6900GZ, PFA 6910GZ, FEP6300GZ, and THV 340Z.

Other suitable fluoropolymer particles are available from suppliers suchas Asahi Glass, Solvay Solexis, and Daikin Industries and will befamiliar to those skilled in the art.

Commercial aqueous dispersion usually contain non-ionic and/or ionicsurfactants at concentration up to 5 to 10 wt. %. These surfactants aresubstantially removed by washing the coagulated blends. A residualsurfactant concentration of less than 1, 0.05, or 0.01 wt. % may bepresent. Quite often it is more convenient to use the “as polymerized”aqueous fluoropolymer-latexes as they do not contain such highercontents of non-ionic/ionic surfactants.

As previously described, the crystalline fluoropolymers have a meltpoint that can be determined by DSC. Crystallinity depends on theselection and concentration of polymerized monomers of thefluoropolymer. For example, PTFE homopolymers (containing 100%TFE-units) have a melting point (Tm) above 340° C. The addition ofcomonomers, such as the unsaturated (per)fluorinated alkyl ethers,reduces the Tm. For example, when the fluoropolymer contains about 3-5wt. % of polymerized units of such comonomer, the Tm is about 310° C. Asyet another example, when the fluoropolymer contains about 15-20 wt. %of polymerized units of HFP, the Tm is about 260-270° C. As yet anotherexample, when the fluoropolymer contains 30 wt. % of polymerized unitsof (per)fluorinated alkyl ethers (e.g. PMVE) or other comonomer(s) thatreduce the crystallinity the fluoropolymer no longer has a detectablemelting point via DSC, and thus is characterized as being amorphous.

In some embodiments, the crystalline fluoropolymer particles contain atleast 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or about 100 wt. %of polymerized units of TFE. Further, the crystalline fluoropolymerparticles typically comprise a lower concentration of unsaturated(per)fluorinated alkyl ethers (e.g. PMVE) than the amorphousflurorpolymer. In typical embodiments, the crystalline fluoropolymerparticles contain less than 30, 25, 20, 15, 10, or 5 wt. % ofpolymerized units of(per)fluorinated alkyl ethers (e.g. PMVE).

In some embodiments, the crystalline fluororpolymers are copolymersformed from the constituent monomers known as tetrafluoroethylene(“TFE”), hexafluoropropylene (“HFP”), and vinylidene fluoride (“VDF,”“VF2,”). The monomer structures for these constituents are shown below:

TFE: CF₂=CF₂  (1)

VDF: CH₂=CF₂  (2)

HFP: CF₂=CF—CF₃  (3)

In some embodiments, the crystalline fluoropolymer consists of at leasttwo of the constituent monomers (HFP and VDF), and in some embodimentsall three of the constituents monomers in varying amounts.

The Tm depends on the amounts of TFE, HFP, and VDF. For example, afluoropolymer comprising about 45 wt. % of polymerized units of TFE,about 18 wt. % of polymerized units of HFP, and about 37 wt. % ofpolymerized units of VDF has a Tm of about 120° C. As yet anotherexample, a fluoropolymer comprising about 76 wt. % of polymerized unitsof TFE, about 11 wt. % of polymerized units of HFP, and about 13 wt. %of polymerized units of VDF has a Tm of about 240° C. By Increasing thepolymerized units of HFP/VDF, while reducing the polymerized units ofTFE, the fluoropolymer becomes amorphous. An overview of crystalline andamorphous Fluoropolymers is given in: Ullmann's Encyclopedia ofIndustrial Chemistry (7^(th) Edition, 2013 Wiley-VCH Verlag. 10.1002/14356007.a11 393 pub 2) Chapter: Fluoropolymers, Organic.

The crystalline fluoropolymer particles and amorphous fluoropolymerparticles may be combined in a variety of ratios. For example, thecoating composition contains about 5 to about 95 weight percentcrystalline fluoropolymer particles and about 95 to about 5 weightpercent amorphous fluoropolymer, based on the total weight percent ofsolids (i.e. excluding the solvent). In some embodiments, the coatingcomposition contains about 10 to about 75 weight percent crystallinefluoropolymer particles and about 90 to about 25 weight amorphousfluoropolymer.

In some embodiments, the coating composition contains about 10 to about50 weight percent crystalline fluoropolymer particles and about 90 toabout 50 weight percent amorphous fluoropolymer. In some embodiments,the coating composition contains about 10 to about 30 weight percentcrystalline fluoropolymer particles and about 90 to about 70 weightpercent amorphous fluoropolymer.

Compositions containing curable fluoroelastomers may further containadditives as known in the art. Examples include acid acceptors. Suchacid acceptors can be inorganic or blends of inorganic and organic acidacceptors. Examples of inorganic acceptors include magnesium oxide, leadoxide, calcium oxide, calcium hydroxide, dibasic lead phosphate, zincoxide, barium carbonate, strontium hydroxide, calcium carbonate,hydrotalcite, etc. Organic acceptors include epoxies, sodium stearate,and magnesium oxalate. Particularly suitable acid acceptors includemagnesium oxide and zinc oxide. Blends of acid acceptors may be used aswell. The amount of acid acceptor will generally depend on the nature ofthe acid acceptor used. Typically, the amount of acid acceptor used isbetween 0.5 and 5 parts per 100 parts of fluorinated polymer.

The fluoropolymer composition may contain further additives, such asstabilizers, surfactants, ultraviolet (“UV”) absorbers, antioxidants,plasticizers, lubricants, fillers, and processing aids typicallyutilized in fluoropolymer processing or compounding, provided they haveadequate stability for the intended service conditions. A particularexample of additives includes carbon particles, like carbon black,graphite, soot. Further additives include but are not limited topigments, for example iron oxides, titanium dioxides. Other additivesinclude but are not limited to clay, silicon dioxide, barium sulphate,silica, glass fibers, or other additives known and used in the art.

In some embodiments, the fluoropolymer composition comprises silica,glass fibers, thermally conductive particles, or a combination thereof.Any amount of silica and/or glass fibers and/or thermally conductiveparticles may be present. In some embodiments, the amount of silicaand/or glass fibers is at least 0.05, 0.1, 0.2, 0.3 wt. % of the totalsolids of the composition. In some embodiments, the amount of silicaand/or glass fibers is no greater than 5, 4, 3, 2, or 1 wt. % of thetotal solids of the composition. Small concentrations of silica can beutilized to thicken the coating composition. Further, smallconcentrations of glass fibers can be used to improve the strength ofthe fluoropolymer film. In other embodiments, the amount of glass fiberscan be at least 5, 10, 15, 20, 25, 35, 40, 45 or 50 wt-% of the totalsolids of the composition. The amount of glass fibers is typically nogreater than 55, 50, 45, 40, 35, 25, 20, 15, or 10 wt. %. In someembodiments, the glass fibers have a mean length of at least 100, 150,200, 250, 300, 350, 400, 450, 500 microns. In some embodiments, theglass fibers have a mean length of at least 1, 2, or 3 mm and typicallyno greater than 5 or 10 mm. In some embodiments, the glass fibers have amean diameter of at least 1, 2, 3, 4, or 5 microns and typically nogreater than 10, 15, 30, or 25 microns. The glass fibers can have aspectratio of at least 3:1, 5:1, 10:1, or 15:1.

In some embodiments, the fluoropolymer composition is free of (e.g.silica) inorganic oxide particles. In other embodiments, thefluoropolymer composition comprises (e.g. silica and/or thermallyconductive) inorganic oxide particles. In some embodiments, the amountof (e.g. silica and/or thermally conductive) inorganic oxide particlesis at least 5, 10, 15, 20, 25, 30, 35, 40, 45 or 50 wt. % of the totalsolids of the composition. In some embodiments, the amount of (e.g.silica and/or thermally conductive) inorganic oxide particles is nogreater than 90, 85, 80, 75, 70, or 65 wt. % of the total solids of thecomposition. Various combinations of silica and thermally conductiveparticles can be utilized. In some embodiments, the total amount of(e.g. silica and thermally conductive) inorganic oxide particles or theamount of a specific type of silica particle (e.g. fused silica, fumedsilica, glass bubbles, etc.) or thermally conductive particle (e.g.boron nitride, silicon carbide, aluminum oxide, aluminum trihydrate) isno greater than 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, or 5 wt. %of the total solids of the composition. Higher concentrations of (e.g.silica) inorganic oxide particles can be favorable to further reducingthe dielectric properties. Thus, the compositions including (e.g.silica) inorganic oxide particles can have even lower dielectricproperties than the crosslinked fluoropolymer alone.

In some embodiments, the (e.g. silica) inorganic oxide particles and/orglass fibers have a dielectric contant at 1 GHz of no greater than 7,6.5, 6, 5.5, 5, 4.5, or 4. In some embodiments, the (e.g. silica)inorganic oxide particles and/or glass fibers have a dissipation factorat 1 GHz of no greater than 0.005, 004, 0.003, 0.002, or 0.0015.

In some embodiments, the composition comprises inorganic oxide particlesor glass fibers that comprise predominantly silica. In some embodiments,the amount of silica is typically at least 50, 60, 70, 75, 80, 85, or 90wt. % of the inorganic oxide particles or glass fibers, In someembodiments, the amount of silica is typically at least 90, 91, 92, 93,94, 95, 96, 97, 98, 99, or greater (e.g. at least 99.5, 99.6, or 99.7)wt-% silica. Higher silica concentrations typically have lowerdielectric constants. In some embodiments, (e.g. fused) silica particlecan further comprise small concentration of other metals/meta oxidessuch as Al₂O₃, Fe₂Os, TiO₂, K₂O, CaO, MgO and Na₂O. In some embodiments,the total amount of such metals/metal oxides (e.g. Al₂O₃, CaO and MgO)is independently no greater than 30, 25, 20, 15, or 10 wt. %. In someembodiments, the inorganic oxide particles or glass fibers may compriseB₂O₃ The amount of B₂O₃ can range up to 25 wt. % of the inorganic oxideparticles or glass fibers. In other embodiments, (e.g. fumed) silicaparticle can further comprise small concentration of additionalmetals/metal oxides such as Cr, Cu, Li, Mg, Ni, P and Zr. In someembodiments, the total amount of such metals or metal oxides is nogreater 5, 4, 3, 2, or 1 wt. %. In some embodiments, the silica may bedescribed as quartz. The amount of non-silica metals or metal oxides canbe determined by uses of inductively coupled plasma mass spectrometry.The (e.g. silica) inorganic oxides particles are typically dissolved inhydrofluoric acid and distilled as H₂SiF₆ at low temperatures.

In some embodiments, the inorganic particles may be characterized as an“agglomerate”, meaning a weak association between primary particles suchas particles held together by charge or polarity. Agglomerate aretypically physically broken down into smaller entities such as primaryparticles during preparation of the coating solution. In otherembodiments, the inorganic particles may be characterized as an“aggregate”, meaning strongly bonded or fused particles, such ascovalently bonded particles or thermally bonded particles prepared byprocesses such as sintering, electric arc, flame hydrolysis, or plasma.Aggregates are typically no broken down into smaller entities such asprimary particles during preparation of the coating solution. “Primaryparticle size” refers to the mean diameter of a single (non-aggregate,non-agglomerate) particle.

The (e.g. silica) particles may have various shapes such as spherical,ellipsoid, linear or branched. Fused and fumed silica aggregates aremore commonly branched. The aggregate size is commonly at least 10× theprimary particle size of discrete part.

In other embodiments, the (e.g. silica) particles may be characterizedas glass bubbles. The glass bubble may be prepared from soda limeborosilicate glass. In this embodiment, the glass may contain about 70percent silica (silicon dioxide), 15 percent soda (sodium oxide), and 9percent lime (calcium oxide). with much smaller amounts of various othercompounds.

In some embodiments, the inorganic oxide particles may be characterizedas (e.g. silica) nanoparticles, having a mean or median particles sizeless than 1 micron. In some embodiments, the mean or median particlesize of the (e.g. silica) inorganic oxide particles is at 500 or 750 nm.In other embodiments, the mean particle size of the (e.g. silica)inorganic oxide particles may be at least 1, 1.5, 2, 2.5, 3, 3.5, 4,4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 or 10 microns. In someembodiments, the mean particle size in no greater than 30, 25, 20, 15,or 10 microns. In some embodiments, the composition comprises little orno (e.g. colloidal silica) nanoparticles having a particle of 100nanometers or less. The concentration of (e.g. colloidal silica)nanoparticles is typically less than (10, 9, 8, 7, 6, 5, 4, 3, 2, or 1wt. %) The inorganic oxide (e.g. silica particle) may comprise a normaldistribution of particle sizes having a single peak or a distribution ofparticles having two or more peaks.

In some embodiments, no greater than 1 wt. % of the (e.g. silica)inorganic oxide particles have a particle size greater than or equal to3 or 4 microns. In some embodiments, no greater than 1 wt. % of the(e.g. silica) inorganic oxide particles have a particle size greaterthan or equal to 5 or 10 microns. In other embodiments, no greater than5, 4, 3, 2, or 1 wt. % of the particles have a particle size greaterthan 45 microns. In some embodiments, no greater than 1 wt. % of theparticles have a particle size ranging from 75 to 150 microns.

In some embodiments, the mean or median particle size refers to the“primary particle size” referring to the mean or median diameter ofdiscrete a non-aggregated, non-agglomerated particles. For example, theparticle size of colloidal silica or glass bubbles is typically the meanor median particle size of In preferred embodiments, the mean or medianparticle size refers to the mean or median diameter of the aggregates.The particle size of the inorganic particles can be measured usingtransmission electron microscopy. The particle size of the fluoropolymercoating solution can be measured using dynamic light scattering.

In some embodiments, the (e.g. silica) inorganic particles have aspecific gravity ranging from 2.18 to 2.20 g/cc.

Aggregated particles, such as in the case of fumed and fused (e.g.silica) particles, can have a lower surface area than primary particlesof the same size. In some embodiments, the (e.g. silica) particle have aBET surface area ranging from about 50 to 500 m²/g. In some embodiments,the BET surface area is less than 450, 400, 350, 300, 250, 200, 150, or100 m²/g. In some embodiments, the inorganic nanoparticles may becharacterized as colloidal silica. It is appreciated that unmodifiedcolloidal silica nanoparticles commonly comprise hydroxyl or silanolfunctional groups on the nanoparticle surface and are typicallycharacterized as hydrophilic.

In some embodiments, (e.g. silica aggregate) inorganic particles andespecially colloidal silica nanoparticles are surface treated with ahydrophobic surface treatment. Common hydrophobic surface treatmentsinclude compounds such as alkoxysilanes (e.g. octadecyltriethoxysilane),silazane, or siloxanes. Various hydrophobic fumed silicas arecommercially available from AEROSIL™, Evonik, and various othersuppliers. Representative hydrophobic fumed silica include AEROSIL™grades R 972, R 805, RX 300, and NX 90 S.

In some embodiments, (e.g. silica aggregate) inorganic particles aresurface treated with a fluorinated alkoxysilane silane compound. Suchcompounds typically comprise a perfluoroalkyl or perfluoropolyethergroup. The perfluoroalkyl or perfluoropolyether group typically has nogreater than 4, 5, 6, 7, 8 carbon atoms. The alkoxysilane group can bebonded to the alkoxy silane group with various divalent linking groupsincluding alkylene, urethane, and —SO₂N(Me)-. Some representativefluorinated alkoxy silanes are described in U.S. Pat. No. 5,274,159 andWO2011/043973; incorporated herein by reference. Other fluorinatedalkoxy silanes are commercially available.

The fluoropolymer compositions may be prepared by mixing the polymer,the curing agent(s) including at least one ethylenically unsaturatedcuring agent, at least one compound with an electron donor group,optional additives and the fluorinated solvent. In some embodiments, thefluoropolymer is first dissolved in the fluorinated solvent and theother additives, including the curing agent(s) and electron donorcompound are added thereafter.

In some embodiments, the fluoropolymer composition comprises thermallyconductive particles.

In some embodiments, the thermally conductive inorganic particles arepreferably an electrically non-conductive material. Suitableelectrically non-conductive, thermally conductive materials includeceramics such as metal oxides, hydroxides, oxyhydroxides, silicates,borides, carbides, and nitrides. Suitable ceramic fillers include, e.g.,silicon oxide, zinc oxide, alumina trihydrate (ATH) (also known ashydrated alumina, aluminum oxide, and aluminum trihydroxide), aluminumnitride, boron nitride, silicon carbide, and beryllium oxide. Otherthermally conducting fillers include carbon-based materials such asgraphite and metals such as aluminum and copper. Combinations ofdifferent thermally conductive materials may be utilized. Such materialsare not electrically conductive, i.e. have an electronic band gapgreater than 0 eV and in some embodiments, at least 1, 2, 3, 4, or 5 eV.In some embodiments, such materials have an electronic band gap nogreater than 15 or 20 eV. In this embodiment, the composition mayoptionally further comprise a small concentration of thermallyconductive particles having an electronic band gap of less than 0 eV orgreater than 20 eV.

In favored embodiments, the thermally conductive particles comprise amaterial having a bulk thermal conductivity >10 W/m*K. The thermalconductivity of some representative inorganic materials is set forth inthe following table.

Thermally Conductive Materials Thermal Electronic Conductivity Band GapMaterial (W/m*K) (eV) Density α-Aluminum Oxide¹ 30 5-9 3.95 g/cc AluminaTrihydrate² 21 2.42-2.45 g/cc Silicon Carbide (SiC)¹ 120  2.4 3.21 g/ccHexagonal Boron 185-300 2.1 2.1 g/cc Nitride (BN)¹

In some embodiments, the thermally conductive particles comprisematerial(s) having a bulk thermal conductivity of at least 15 or 20W/m*K. In other embodiments, the thermally conductive particles comprisematerial(s) having a bulk thermal conductivity of at least 25 or 30W/m*K. In yet other embodiments, the thermally conductive particlescomprise material(s) having a bulk thermal conductivity of at least 50,75 or 100 W/m*K. In yet other embodiments, the thermally conductiveparticles comprise material(s) having a bulk thermal conductivity of atleast 150 W/m*K. In typical embodiments, the thermally conductiveparticles comprise material(s) having a bulk thermal conductivity of nogreater than about 350 or 300 W/m*K.

Thermally conductive particles are available in numerous shapes, e.g.spheres and acicular shapes that may be irregular or plate-like. In someembodiments, the thermally conductive particles are crystals, typicallyhave a geometric shape. For example, boron nitride hexagonal crystalsare commercially available from Momentive. Further, alumina trihydrateis described as a hexagonal platelet. Combinations of particles withdifferent shapes may be utilized. The thermally conductive particlesgenerally have an aspect ratio less than 100:1, 75:1, or 50:1. In someembodiment, the thermally conductive particles have an aspect ratio lessthan 3:1, 2.5:1, 2:1, or 1.5:1. In some embodiments, generallysymmetrical (e.g., spherical, semi-spherical) particles may be employed.

Boron nitride particles are commercially available from 3M as “3M™ BoronNitride Cooling Fillers”.

In some embodiments, the boron nitride particles has a bulk density ofat least 0.05, 0.01, 0.15, 0.03 g/cm³ ranging up to about 0.60, 0.70, or0.80 g/cm³. The surface area of the boron nitride particle can be <25,<20, <10, <5, or <3 m²/g. The surface area is typically at least 1 or 2m²/g.

In some embodiments, the particle size, d(0.1), of the boron nitride(e.g. platelet) particles ranges from about 0.5 to 5 microns. In someembodiments, the particle size, d(0.9), of the boron nitride (e.g.platelet) particles is at least 5 ranging up to 20, 25, 30, 35, 40, 45,or 50 microns.

The coating composition described herein including fluorinated solventis “stable, meaning that the coating composition remains homogeneouswhen stored for at least 24 hours at room temperature in a sealedcontainer. In some embodiments, the coating composition is stable forone week or more. “Homogeneous” refers to a coating composition thatdoes not exhibit a visibly separate precipitate or visibly separatelayer when freshly shaken, placed in a 100 ml glass container andallowed to stand at room temperature for at least 4 hours.

In some embodiments, the fluoropolymer is first combined with othersolid ingredients and in particular with the electron donor (e.g. amine)compounds and ethylenically unsaturated curing agent described herein,as well as the (e.g. silica) inorganic particles when present. Thefluoropolymer and amine compounds can be combined in conventional rubberprocessing equipment to provide a solid mixture, i.e. a solid polymercontaining the additional ingredients, also referred to in the art as a“compound”. Typical equipment includes rubber mills, internal mixers,such as Banbury mixers, and mixing extruders. During mixing thecomponents and additives are distributed uniformly throughout theresulting fluorinated polymer “compound” or polymer sheets. The compoundis then preferably comminuted, for example by cutting it into smallerpieces and is then dissolved in the solvent.

The fluoropolymer coating solution compositions provided herein aresuitable for coating substrates. The fluoropolymer coating solutioncompositions may be formulated to have different viscosities dependingon solvent and fluoropolymer content and the presence or absence ofoptional additives. The fluoropolymer coating solution compositionstypically contain or are solutions of fluoropolymers and may be in theform of liquids or pastes. Nevertheless, the compositions may containdispersed or suspended materials but these materials preferably areadditives and not fluoropolymers of the type as described herein.Preferably, the compositions are liquids and more preferably they aresolutions containing one or more fluoropolymer as described hereindissolved in a solvent as described herein.

The fluoropolymer compositions provided herein are suitable for coatingsubstrates and may be adjusted (by the solvent content) to a viscosityto allow application by different coating methods, including, but notlimited to spray coating or printing (for example but not limited toink-printing, 3D-printing, screen printing), painting, impregnating,roller coating, bar coating, dip coating and solvent casting.

Coated substrates and articles may be prepared by applying thefluoropolymer compositions to a substrate and removing the solvent. Thecuring may occur to, during, or after removing the solvent. The solventmay be reduced or completely removed, for example for evaporation,drying or by boiling it off. After removal of the solvent thecomposition may be characterized as “dried”.

Methods of making a crosslinked fluoropolymer described herein comprisecuring the fluoropolymer with (e.g. UV or e-beam) actinic irradiation.The fluoropolymer composition, substrate, or both are transmissive tothe curing radiation. In some embodiments, a combination of UV curingand thermal (e.g. post) curing is utilized. The curing is carried out atan effective temperature and effective time to create a curedfluoroelastomer. Optimum conditions can be tested by examining thefluoroelastomer for its mechanical and physical properties. Curing maybe carried out under pressure or without pressure in an oven. A postcuring cycle at increased temperatures and or pressure may be applied toensure the curing process is fully completed. The curing conditionsdepend on the curing system used.

In some embodiments, the composition is cured by UV-curing. Thefluoropolymers of the compositions described here comprise little or nopolymerized units of vinylidene fluoride (VDF) (i.e. CH₂=CF₂) or VDFcoupled to hexafluoropropylene (HFP). Polymerized units of VDF canundergo dehydrofluorination (i.e. an HF elimination reaction) asdescribed in US2006/0147723.

The reaction is limited by the number of polymerized VDF groups coupledto an HFP group contained in the fluoropolymer. The double bonds createdas a result of dehydrofluorination can then react (via Michael addition)with an amino alkoxy silane thereby grafting fluorinated pendent alkoxysilane groups onto the fluoropolymer backbone. When irradiated with UVlight, such pendent groups can free-radically copolymerize withmultifunctional (meth)acrylate compounds.

However, since the fluoropolymers of the compositions described herecomprise little or no polymerized units of VDF (i.e. CH₂=CF₂) coupled toan HFP group, the fluoropolymers are not susceptible to the reactionschemes just described. As evident by the forthcoming examples, theamine compound alone can initiate UV-curing in the absence offree-radical photoinitiators. The inclusion of free-radicalphotoinitiator typically does not increase the crosslinking of thefluoropolymer. This result suggests that the fluoropolymer is notcrosslinked via a free-radical mechanism.

Although, conventional free-radical initiators are not required, thecomposition can optionally further comprise a photoinitiator. In otherembodiments, the composition is substantially free of free-radicalinitiators including such free-radical photoinitiators.

In some embodiments, the UV radiation may have sufficient intensity at awavelength of at least 190 nm, 200 nm, 210 nm, 220 nm, 230 nm or 240 nm.In some embodiments, the UV radiation may have sufficient intensity at awavelength no greater than 350 nm, 340 nm, 330 nm, 320 nm, 310 nm, or290 nm. In some embodiments, the (e.g. UV) actinic radiation hassufficient intensity at a wavelength ranging from 270-290 nm such thatin the presence of an (e.g. amine) electron donor a wavelength-inducedsingle electron transfer reaction may occur between C-I bonds. In someembodiments, the UV radiation may have sufficient intensity at awavelength ranging below 240 nm (e.g. 150-200 nm) such that in thepresence of an (e.g. amine) electron donor a wavelength-induced singleelectron transfer reaction may occur between C—Cl or C—Br bonds.

UV light sources can be of various types. Low light intensity sources,such as blacklights, generally provide intensities ranging from 0.1 or0.5 mW/cm²(milliwatts per square centimeter) to 10 mW/cm² (as measuredin accordance with procedures approved by the United States NationalInstitute of Standards and Technology as, for example, with a UVIMAP UM365 L-S radiometer manufactured by Electronic Instrumentation &Technology, Inc., in Sterling, VA). High light intensity sourcesgenerally provide intensities greater than 10, 15, or 20 mW/cm² rangingup to 450 mW/cm² or greater. In some embodiments, high intensity lightsources provide intensities up to 500, 600, 700, 800, 900 or 1000mW/cm². UV light to polymerize the ethylenically unsaturated monomer(s)can be provided by various light sources such as light emitting diodes(LEDs), fluorescent blacklights, arc-lamps such as xenon-acrc lamps andmedium and low pressure mercury lamps (including germicidal lamps),microwave-driven lamps, lasers etc. or a combination thereof. Thecomposition can also be polymerized with higher intensity light sourcesas available from Fusion UV Systems Inc. Lamps that emit ultraviolet orblue light are typically preferred. The UV exposure time forpolymerization and curing can vary depending on the intensity of thelight source(s) used. For example, complete curing with a low intensitylight course can be accomplished with an exposure time ranging fromabout 30 to 300 seconds; whereas complete curing with a high intensitylight source can be accomplished with shorter exposure time ranging fromabout 5 to 20 seconds. Partial curing with a high intensity light sourcecan typically be accomplished with exposure times ranging from about 2seconds to about 5 or 10 seconds. In some embodiments, post curing maybe carried out at a temperature between 170° C. and 250° C. for a periodof 0.1 to 24 hours.

In some embodiments, post curing of the fluoropolymer may optionally becarried out at lower temperatures. Post curing at lower temperatures isamenable for coating heat sensitive substrates. In some embodiments, thepost curing occurs at a temperature ranging from 100, 110, 120, 130, 135or 140° C. up to 170° C. for a period of 5-10 minutes to 24 hours. Insome embodiments, the temperature is no greater than 169, 168, 167, 166,165, 164, 163, 162, 161, or 160° C. In some embodiments, the temperatureis no greater than 135, 130, 125, or 120° C. In favored embodiments,after curing the fluoropolymer is sufficiently crosslinked such that atleast 80, 85, 90, 95 or 100 wt. % or greater cannot be dissolved (within12 hours at 25° C.) in fluorinated solvent (e.g. 3-ethoxy perfluorinated2-methyl hexane) at a weight ratio of 5 grams of fluoropolymer in 95% byweight of fluorinated solvent.

The compositions may be used for impregnating substrates, printing onsubstrates (for example screen printing), or coating substrates, forexample but not limited to spray coating, painting dip coating, rollercoating, bar coating, solvent casting, paste coating. The substrate maybe organic, inorganic, or a combination thereof. Suitable substrates mayinclude any solid surface and may include substrate selected from glass,plastics (e.g. polycarbonate), composites, metals (stainless steel,aluminum, carbon steel), metal alloys, wood, paper among others. Thecoating may be coloured in case the compositions contains pigments, forexample titanium dioxides or black fillers like graphite or soot, or itmay be colorless in case pigments or black fillers are absent.

Bonding agents and primers may be used to pretreat the surface of thesubstrate before coating. For example, bonding of the coating to metalsurfaces may be improved by applying a bonding agent or primer. Examplesinclude commercial primers or bonding agents, for example thosecommercially available under the trade designation CHEMLOK.

Articles containing a coating from the compositions provided hereininclude but are not limited to impregnated textiles, for exampleprotective clothing. Another example of an impregnated textile is aglass scrim impregnated with the (e.g. silica containing) fluoropolymercomposition described herein. Textiles may include woven or non-wovenfabrics. Other articles include articles exposed to corrosiveenvironments, for example seals and components of seals and valves usedin chemical processing, for example but not limited to components orlinings of chemical reactors, molds, chemical processing equipment forexample for etching, or valves, pumps and tubings, in particular forcorrosive substances or hydrocarbon fuels or solvents; combustionengines, electrodes, fuel transportation, containers for acids and basesand transportation systems for acids and bases, electrical cells, fuelcells, electrolysis cells and articles used in or for etching.

An advantage of the coating compositions described herein is that thecoating compositions can be used to prepare coatings or fluoropolymersheets of high or low thickness. In some embodiments, the dried andcured fluoropolymer has a thickness of 0.1 microns to 1 or 2 mils. Insome embodiments, the dried and cured fluoropolymer thickness is atleast 0.2, 0.3, 0.4, 0.5, or 0.6 microns. In some embodiments, the driedand cured fluoropolymer thickness is at least 1, 2, 3, 4, 5, or 6microns.

In typical embodiments, the dried and cured (i.e. crosslinked)composition has a low dielectric constant (Dk), typically less than2.75, 2.70, 2.65, 2.60, 2.55, 2.50, 2.45, 2.40, 2.35, 2.30, 2.25, 2.20,2.15, 2.20, 2.15, 2.10, 2.05, 2.00, 1.95, 1.90. In some embodiments, thedielectric constant is at least 2.02, 2.03, 2.04, 2.05. The dried andcured (i.e. crosslinked) composition has a low dielectric loss,typically less than 0.01, 0.009, 0.008, 0.007, 0.006, 0.005, 0.004,0.003, 0.002, 0.001, 0.0009, 0.0008, 0.0007, 0.0006, 0.0005, 0.0004,0.0003. In some embodiments, the dielectric loss is at least 0.00022,0.00023, 0.00024, 0.00025.

The dried and cured coating can exhibit good adhesion to varioussubstrates (e.g. glass, polycarbonate,), as evidence by the coatingexhibiting a 2, and preferably a 3 or 4 according to the Boiling WaterTest described in PCT/US2019/036460. In favored embodiments, the driedand cured coating is durable as evidence by the coating exhibiting a 2,and preferably a 3 or 4 according to the Abrasion Test described inpreviously cited PCT/US2019/036460. In some embodiments, the coating isdurable, according to the Abrasion Test after being subjected to theBoiling Water Test.

The dried and cured coating can exhibit good adhesion to metals, such ascopper. For example, in some embodiments, the T-peel to copper foil isat least 0.1, 0.2, 0.3, 0.4, 0.5 or 0.6 N/mm ranging up to at least 1N/mm (i.e. 10 N/cm), 1.5 N/mm 2 N/mm or 2.5 N/mm as determined by thetest method described in the examples.

In some embodiments, the dried and cured coating has good hydrophobicand oleiphobic properties according to the Black Permanent MarkerResistance Test described in previously cited PCT/US2019/036460, i.e.the marker fluid beads and is easy to remove with a paper towel orcloth.

In some embodiments, the dried and cured coating has good hydrophobicand oleiphobic properties, as determined by Contact Angle Measurements(as determined according to the test method described in the examples).In some embodiments, the static, advancing and/or receding contact anglewith water can be at least 100, 105, 110, 115, 120, 125 and typically nogreater than 130 degrees. In some embodiments, the advancing and/orreceding contact angle with hexadecane can be at least 60, 65, 70, or 75degrees. In some embodiments, the coating exhibits such contact angles,after being subjected to the Boiling Water Test or after being subjectthe Boiling Water Test and the Abrasion Test (as determined according tothe test method described in previously cited PCT/US2019/036460).

In some embodiments, the dried and cured coating exhibits good corrisionresistance (i.e. not corroded) according to the Acid/Base Corrison Testdescribed in previously cited PCT/US2019/036460.

In some embodiments, the dried and cured coating (e.g. film) exhibitslow water absorption e.g. less than 0.5, 0.4, 0.3, 0.2, or 0.1 asdetermined by the Moisture Uptake test method described in the examples.

In some embodiments, the composition exhibits a low coefficient ofthermal expansion e.g. less than 150, 100, 50, 40, 30, 20 or 10 asdetermined by the test method described in the examples. For someinsulation layer uses the coefficient of thermal expansion is lesscritical and may range up to 175, 200 or 225.

As used herein the term “partially fluorinated alkyl” means an alkylgroup of which some but not all hydrogens bonded to the carbon chainhave been replaced by fluorine. For example, an F₂HC-, or an FH₂C-groupis a partially fluorinated methyl group. Alkyl groups where theremaining hydrogen atoms have been partially or completely replaced byother atoms, for example other halogen atoms like chlorine, iodineand/or bromine are also encompassed by the term “partially fluorinatedalkyl” as long as at least one hydrogen has been replaced by a fluorine.For example, residues of the formula F₂ClC- or FHClC-are also partiallyfluorinated alkyl residues.

A “partially fluorinated ether” is an ether containing at least onepartially fluorinated group, or an ether that contains one or moreperfluorinated groups and at least one non-fluorinated or at least onepartially fluorinated group. For example, F₂HCO—CH₃, F₃CO—CH₃,F₂HC—O—CFH₂, and F₂HC—O—CF₃ are examples of partially fluorinatedethers. Ethers groups where the remaining hydrogen atoms have beenpartially or completely replaced by other atoms, for example otherhalogen atoms like chlorine, iodine and/or bromine are also encompassedby the term “partially fluorinated alkyl” as long as at least onehydrogen has been replaced by a fluorine. For example, ethers of theformula F₂ClC—O—CF₃ or FHClC—O—CF₃ are also partially fluorinatedethers.

The term “perfluorinated alkyl” or “perfluoro alkyl” is used herein todescribe an alkyl group where all hydrogen atoms bonded to the alkylchain have been replaced by fluorine atoms. For example, F₃C-representsa perfluoromethyl group.

A “perfluorinated ether” is an ether of which all hydrogen atoms havebeen replaced by fluorine atoms. An example of a perfluorinated ether isF₃C—O—CF₃.

The following examples are provided to further illustrate the presentdisclosure without any intention to limit the disclosure to the specificexamples and embodiments provided.

EXAMPLES

Unless otherwise noted or readily apparent from the context, all parts,percentages, ratios, etc. in the Examples and the rest of thespecification are by weight.

TABLE 1 Materials: Abbreviation Name Source PFE-1 Coagulated gumobtained from 30 wt. % solids 3M Dyneon aqueous perfluoroelastomerlatex - 50.4 wt. % PMVE, 49.6 wt. % TFE, and 0.4 wt. % iodine, having aMooney value of 40 as can prepared according to WO2015/088784 orWO2015/134435, PFE-2 Coagulated gum obtained from 34 wt. % solids 3MDyneon aqueous perfluoroelastomer latex - 49 wt. % PMVE, 51 wt. % TFE,0.4 wt. % bromine, having a Mooney value of 60. PFE-3 Perfluoroelastomerlatex or coagulated gum 3M Dyneon comprising a copolymer of 65.8 mol %TFE, 33 mol PMVE, 1.2 mol % of a nitrile vinylether Novec 7500 3-ethoxyperfluorinated 2-methyl hexane 3M EMSD (HFE-7500) Novec 7300 3-methoxyperfluorinated 4-methyl petane 3M EMSD (HFE-7300) APES/APS(3-Aminopropyl)triethoxysilane Aldrich TMDABN,N,N′,N′-Tetramethyl-1,4-diamino butane Aldrich BTMP-Me-ABis(3-trimethoxysilylpropyl)-n-methylamine Gelest Corporation AminesDiamino hexane, N,N-dimethyl aniline, Aldrich Triethylenetetramine,Diethylenetriamine ATES Allyltriethoxysilane Aldrich DADMSDiallydimethylsilane Gelest Corporation DVTM-D- 1,3-Divinyltetramethyldisiloxane Gelest siloxane Corporation Me-Ac-PTMS 3-(Methacryloylpropyl)trimethoxysilane Gelest Corporation N-Me-APMS N-methylaminopropyltrimethoxysilane Gelest Corporation TMOS Tetramethyl orthosilicateAldrich Darocure 1173 2-hydroxy-2-methyl-1-phenyl-1-propanone BASF or1173 photoinitiator THV340 3M, DYNEON Fluoroplastic Dispersion THV 340Z,3M Dyneon Tm = 140° C. 50 wt. % solids diluted to 30 wt. % solids THV-230 wt. % solids aqueous polymer latex - 59 wt. % TFE, 3M Dyneon 19 wt. %HFP, 22 wt. % VDF, Tm = 165° C., MFI (265° C./5 kg) 10.5 g/10 min as canbe prepared according to EP1155055 or U.S. Pat. No. 5,463,021 THV-1 30wt. % solids aqueous polymer latex 76 wt. % TFE, 3M Dyneon 11 wt. % HFP,13 wt. % VDF, Tm = 236° C., MFI (265° C./5 kg) 10.5 g/10 min as can beprepared according to EP1155055 or U.S. Pat. No. 5,463,021 PFA 30 wt. %solids aqueous latex - 96 wt. % TFE, 4 wt. % 3M Dyneon PPVE, Tm is 308°C., MFI (372° C./5 kg) 7 g/10 min PFA-2 Latex (30 w % solids) comprisinga polymer of TFE 3M Dyneon (97 w %), PMVE (CF₂═CF—O—CF₃, 2 w %) andCF₂═CF—CF₂—O—C₃F₇ (1 w %), melting point 307° C., MFI (372° C./5 kg) 2g/10 min PTFE 20 wt. % solids aqueous PTFE homopolymer latex, 3M DyneonTm = 342° C., as can be prepared according to EP1155055 CQ0382 Fusedsilica with surface treatment (D90 = 4 um) Suzhou Ginet CQ1082 Fusedsilica with surface treatment (D90 = 12 um) Suzhou Ginet FS 20 3M ™Fused Silica 20 (9-16 um) 3M FS 550 3M ™ Fused Silica 550 (3.5-5.2 um)3M GB 3M ™ Glass Bubbles iM16K (20 um) 3M FG-Si Fine ground silica USSilica Co (MIN-U-SIL 5, D90 = 3.5 um) BTESPA Bis(triethoxylsilyl)propylamine, Gelest NH(C3H6Si(OEt)3)2 TEOS Tetraethoxysilane, (EtO)4Si AldrichC4-Si C4F9SO2NMeCH2CH2CH2Si(OMe)3, Prepared by 3M the proceduredescribed in Ex-6 of U.S. Pat. No. 5,274,159, except usingC₄F₉SO₂NMeCH₂CH═CH₂ for replacement of C₈F₁₇SO₂NEtCH₂CH═CH₂ C6-SiC6F13CH2CH2Si(OEt)3, DYNASYLAN F8261 Evonic HFPO-SiF(CF(CF3)CF2O)n-CF(CF3)CO2NH- Surfactis CH2CH2CH2Si(OMe)3, (MW~1155)Technologies TAIC Triallyl isocyanuirate, SR533 Sartomer QF Quartzfiber, 3 mm length, 8 um diameter Shenjiu RL Film Release Liner film,RF02N-3 mil 3M FEP Film Fluoropolymer film DuPont PFA Film Fluoropolymerfilm DuPont BTMSPA Bis(3-trimethoxysilylpropyl)amine Gelest CorporationTFM-2 Latex (23 w % solids) comprising a PTFE modified 3M Dyneon with0.4 w % PPVE and CF₂═CF—O—(CF₂)₅CN (<0.05 w %) FlorinatedPerfluoroamidine; obtained under the trade 3M Dyneon amidine designation3M DYNEON PFE 300Z BN CFP 012 Boron Nitride powder 3M BN CFP 0075 BoronNitride powder 3M FG6616 Microglass 6616 (Milled E-glass filaments)Fibertec (Bridgewater, MA) FG6608 Microglass 6608 (Milled E-glassfilaments) Fibertec FG3004 Microglass 3004 (Milled E-glass filaments)Fibertec Wallonites Tremin 939-100 MST The Mineral Engineers FT9110Microglass 9110 (Milled E-glass filaments) Fibertec FT9114 Microglass9114 (Milled E-glass filaments) Fibertec PFE301C PFE catalyst obtainedunder the trade designation 3M 3M Dyneon DYNEON PFE 301C CQ0282 Fusedsilica (D90 = 3 microns; Average = 1-2 Suzhou Ginet microns) PFA-3 Latexor coagulated solid comprising a copolymer of TFE/PPVE/nitrilvinyletheras can be prepared according to Fluoroplastic C of U.S. Pat. No.7,019,083 PTFE5033 Commercial product obtained under the trade 3M Dyneondesignation 3M DYNEON PTFE DISPERSION TF 5033Z; particle size about 200nm

Preparation of Fluorinated Ether Diene

A fluorinated ether diol, HO—CH₂—CF₂—O—(CF₂CF₂)CF₂—CH₂—OH (0.16 mol),having an average molecular weight of 1500, and an average hydroxylfunctionality of 1.8 as described in U.S. Pat. No. 5,384,374 was allowedto react with sodium methoxide (0.34 mol) and subsequently to react withallyl bromide (40 g, 0.36 mol) in a 250 mL 3-necked flask with acondenser at 60° C. overnight. After reaction, the reaction mixture waswashed with water and a pale-yellow liquid was dried over CaCl₂) beforerotavapor to remove any residue of ally bromide.

General Procedure—Perfluoroelastomer PFE Coating Solution Preparationwith Multifunctional Alkene/Aminosilane Ester Photocrosslinkers:

Perfluoroelastomer PFE-1 and PFE-2 solutions were prepared by cuttinggums separately into small pieces and adding them into HFE solvent(HFE-7300 or HFE-7500) to make a 10 wt. % PFE in HFE solution (10 g PFEand 90 g HFE). The containers were sealed with PTFE tape and paraffinfilm. The solution was subject to vigorous shaking overnight (˜12 hours)to become completely homogenous.

All the aminosilanes, initiators were dissolved or dispersed in HFE toform 1 wt. % or 5 wt. % solutions or suspensions (e.g. 0.5 g TAIC wasadded to 9.5 g HFE to form a 5 wt. % suspension in a vial). To the PFEsolution was added an amine (e.g. aminosilane), an alkene and,optionally, a photo-initiator. For example, sample (5% TAIC, 1% APES, 2%TMOS) was prepared by adding 0.3157 g TAIC suspension (5 wt. % in HFE),0.0606 g APES suspension (5 wt. % in HFE), and 0.1224 g TMOS solution (5wt. % in 7500) to 3 g PFE-1 solution (10 wt. % in PFE-1). Many silanesform suspensions, rather than solutions in HFE. Such suspensions werehomogenized using a vortex shaker at 1000 rpm for 10 seconds to formwell dispersed slurry before being added to the PFE-HFE solution. Also,the percentage in the formula (e.g., 5/a, 3%, 1%) was the mass fractionbased on the solid content of PFE (e.g. PFE-1+5% APES+2% 1173 means: thesolid content of PFE-1/APES=95:5 and the solid content ofPFE-1/1173=98:2)

General Procedure—Perfluoroelastomer PFE Coating Solution Preparationwith Fluorinated Alkene/Aminosilane Ester Photo-Crosslinkers:

In a similar fashion as described above, perfluoroelastomer PFE-1 andPFE-2 solutions were prepared by cutting gums separately into smallpieces and placing them into HFE solvent to obtain 10 wt. % solutions ofPFE in HFE in a glass jar. The glass jar was sealed with Teflon tape andparaffin film. The solution was subjected to vigorous shaking overnight(˜12 hours) until completely homogenous. Most alkenes were dissolved ordispersed in HFE to form 1 wt. % or 5 wt. % solution or suspension.Alkenes were dissolved in methanol or methoxy propanol instead whenthere was rapid phase separations between the alkenes and HFE solutionand when the alkene sample was solid at room temperature and could notbe completely dispersed in HFE-7500. These alkenes include4,4′-bis((1,2,2-trifluorovinyl)oxy)-1,1′-biphenyl (dissolved inmethanol), Chloro-1,2-phenylene diacrylate (dissolved in methanol),Perchloro-1,2-phenylene diacrylate (dissolved in methoxy propanol),2,4,6-tribromobenzene-1,3,5-triyl triacrylate (dissolved in methoxypropanol)). In addition to alkenes, all the silanes and photoinitiatorswere dissolved or dispersed in HFE to form 1 wt. % or 5 wt. % solutionsor suspensions. To PFE was added an alkene or a multifunctional alkeneand other chemicals including silanes and initiators as indicated inTables.

Split Post Dielectric Resonator Measurements at 25 GHz

All split-post dielectric resonator measurements were performed inaccordance with the standard IEC 61189-2-721 near a frequency of 25 GHz.Each thin material or film was inserted between two fixed dielectricresonators. The resonance frequency and quality factor of the posts areinfluenced by the presence of the specimen, and this enables the directcomputation of complex permittivity (dielectric constant and dielectricloss). The geometry of the split dielectric resonator fixture used inour measurements was designed by the Company QWED in Warsaw Poland. This25 GHz resonator operates with the TE_(0ld) mode which has only anazimuthal electric field component so that the electric field remainscontinuous on the dielectric interfaces. The split post dielectricresonator measures the permittivity component in the plane of thespecimen. Loop coupling (critically coupled) was used in each of thesedielectric resonator measurements. This 25 GHz Split Post Resonatormeasurement system was combined with Keysight VNA (Vector NetworkAnalyzer Model PNA 8364C 10 MHz-50 GHz). Computations were performedwith the commercial analysis Split Post Resonator Software of QWED toprovide a powerful measurement tool for the determination of complexelectric permittivity of each specimen at 25 GHz

Coefficient of Thermal Expansion (CTE) Measurement

CTE measurements were conducted using a Thermomechanical Analyzer (TMA)TMA Q400 from TA Instrument. The film samples were cut into rectangleshapes (4.5 mm×24 mm) and mounted on the tension clamp. The samples wereheated to at least 150° C. using a ramp rate of 3.00° C./min and thencooled to room temperature at the same rate. Then the samples wereheated again to the target temperature. The CTE calculated from thesecond cycle was reported.

Moisture Uptake Measurement

Water absorption measurements were made using a vapor absorptionanalysis instrument Q500SA from TA Instrument. The sample was placed ina quartz pan located inside a programmable chamber. Approximately 5 mgof sample was used in each measurement. The samples were first dred inthe chamber until the weight remained unchanged over 20 min. Then thesamples were placed under 60° C. and 50% humidity conditions untilweight equilibrium was achieved. The water absorption value wascalculated based on the weight increase/original weight of the sample.

T-Peel Measurement

Films were laminated with a Cu foil under 24° C. for 20 min. Thelaminated samples were cut into strips with 0.5 inch width for T-peelmeasurement. The measurand was conducted using an INSTRONelectromechanical universal testing machine using ASTM D1876 standardmethod.

Static Contact Angle

Static contact angle measurements were made using deionized water on adrop shape analyzer DSA100 from KRUSS, Germany. Reported values were theaverage of measurements on at least three drops measured on the rightand the left sides of the drops. Drop volumes were 5 μL for staticmeasurements.

Table 2. Crosslinking Yield of Cured Fluoropolymers

For the crosslinking yield studies, samples were prepared by depositinga 3 g solution onto PET film. The coated film was dried at ambienttemperature for 2 hours and at 50° C. for 20 min. After the samples werecompletely dried, the PET film samples were placed on a wooden or astainless steel board and cured under a single 500 watt H-bulb or 500watt D-bulb UV lamp for 5-10 runs with a speed of 30 ft per minute (asindicated in the tables). After UV curing, many samples were alsothermally cured at 120° C. for 5 min in an oven (as indicated intables). Some of the same samples were also subjected to thermal curingconditions without UV curing.

The UV cured samples (1-2 mils in thickness) were peeled off from thePET film, weighed, and then dissolved with HFE in a vial. The mass ratioof cured PFE sample/HFE solvent was 5/95. The vial was subjected tovigorous shaking overnight (˜12 hours) before any observation wasrecorded as described in the following table. The precipitated samples(i.e. crosslinked PFE) in the HFE solutions were collected, dried andweighed. In some instances, the gel (i.e. less crosslinked PFE) wascollected, dried, and weighed.

Extent of Crosslinking Description Soluble Completely soluble or most ofsample is dissolved Viscosity Partially soluble, HFE solution becomesviscous, builds up small amount of precipitate (like small flakes orsilks), inseparable Swell, Noticeable precipitation, largely~mediallyswell, low yield however a significant amount of sample is dissolved GelSample takes on the appearance of gel, largely swell, inseparable ordifficult to separate Swell Insoluble, apparent swell and increase involume, the HFE solution is viscous, inseparable or difficult toseparate Swell wt. % Insoluble, apparent swell and increase in volume,the HFE solution is viscous, separable Precipitate Completely insoluble,a little to no swell, Intact film, HEF has very low viscosity, separable

TABLE 3 Effect of an aminosilane ester on photochemically crosslinkingPFE-1 with TAIC UV cured Thermally 10 times + cured at 120 120° C. ° C.5 min 5 min Comparative Examples TAIC or aminosilane Controls A % TAIC —Gel B 2.5% TAIC Soluble Swell C 1% APES soluble Swell, low yieldExamples TAIC + Primary amine 3.1 2% TAIC 0.5% APES — Precipitate 97.42wt. % 3.2 2.5% TAIC 1% APES Soluble Precipitate 96.74 wt. % 3.3 5% TAIC0.5% APES Soluble Precipitate 97.37 wt. % 3.4 5% TAIC 1% APES SolublePrecipitate 97.51 wt. % 3.5 5% TAIC 1% APES 2% TMOS Soluble Precipitate97.85 wt. % 3.6 5% TAIC 3% APES — Precipitate 98.89 wt. % TAIC +Secondary amine 3.7 5% TAIC 1% BTEPA — Precipitate 95.52 wt. % 3.8 5%TAIC 0.5% BTEPA — Precipitate 97.45 wt. % 3.9 2% TAIC 0.5% BTEPAPrecipitate 95.84 wt. % 3.10 2.5% TAIC 2.5% N-Me-APMS SolublePrecipitate 93.44 wt. % 3.11 5% TAIC 0.5% N-Me-APMS — Precipitate 98.28wt. % 3.12 5% TAIC 1% N-Me-APMS Soluble Precipitate 96.72 wt. % 3.13 5%TAIC 1% N-Me-APMS — Precipitate 92.86 wt. % 3.14 2% TAIC 0.5% N-Me-APMS— Precipitate 90.35 wt. % TAIC + Tertiary amine 3.15 5% TAIC 0.5%BTMP-Me-A — Precipitate 98.62 wt. % 3.16 5% TAIC 1% BTMP-Me-A —Precipitate 98.40 wt. % 3.17 2% TAIC 0.5% BTMP-Me-A — Precipitate 93.27wt. % 3.18 5% TAIC 1% N,N-DIME-APMS — Precipitate 89.33 wt. %

TABLE 4 Effect of an organic amine on photochemically crosslinking PFE-1with TAIC UV cured 10 times + Examples 120° C. 5 min TAIC + Primaryorganic amine 4.1 5% TAIC 1% Diamino hexane Precipitate 81.33 wt. %TAIC + Tertiary organic amine 4.2 5% TAIC 1% TMDAB Precipitate 87.14 wt.% 4.3 5% TAIC 1% N,N-dimethyl aniline Swell 75.44 wt. % TAIC + Primary +Secondary organic amine 4.4 5% TAIC 1% Triethylenetetramine Precipitate98.95 wt. % 4.5 5% TAIC 1% Diethylenetriamine Swell 80.05 wt. %

TABLE 5 Effect of alkenes on photochemically crosslinking PFE-1 withTAIC UV cured 120° C. 10 times + Examples 5 min 120° C. 5 min Allylsilane 5.1 5% DADMS 1% APES 2%1173 Soluble Swell 61.39 wt. % 5.2 5%DADMS 1% APES — Swell 72.76 wt. % Allyl 5.3 5% ATES Control SolubleSwell 56.95 wt. % 5.4 5% ATES 0.5% APES Soluble Precipitate 90.69 wt. %5.5 5% ATES 1% APES Soluble Precipitate 86.17 wt. % 5.6 5% ATES 1% BTEPA— Precipitate 85.07 wt. % 5.7 5% ATES 1% BTMP-Me-A — Swell 65.13 wt. %Acryloyl silane 5.8 5% Me-Ac-PTMS 5% APES — Precipitate 2% 1173 5.9 5%Me-Ac-PTMS 5% APES — Precipitate 5% 1173 5.10 5% Me-Ac-PTMS 2% 1173 —Swell 57.63 wt. % Control 5.11 5% Me-Ac-PTMS 1% APES — Swell 62.90 wt. %5.12 5% Me-Ac-PTMS 1% APES — Swell 61.02 wt. % 2% 1173 Multifunctionalolefin 5.13 5% Triallylamine 1% APES Soluble Precipitate 67.62 wt. %5.14 5% Triallylamine Soluble Swell 63.06 wt. % 0.5% APES 2% 1173 5.155% Triallylamine Soluble Swell 67.89 wt. % 1% APES 2% 1173 Vinylsiloxane 5.16 5% DVTM-D-siloxane Soluble Swell 83.01 wt. % 1% APES 2%1173

TABLE 6 Influence of wavelength (H-Bulb and D-Bulb) and the number of UVcure runs on UV crosslinking of PFE-1 + TAIC + APES Examples H-BulbD-Bulb 6.1 5% TAIC 1% APES Precipitate Precipitate (UV × 2 + 120° C. 5min) 89.04 wt. % 88.02 wt. % 6.2 5% TAIC 1% APES Precipitate Precipitate(UV × 4 + 120° C. 5 min) 97.72 wt. % 96.80 wt. % 6.3 5% TAIC 1% APESPrecipitate Precipitate (UV × 4) 86.50 wt. % 86.65 wt. % 6.4 5% TAIC 1%APES Precipitate Precipitate (UV × 6 + 120° C. 5 min) 98.00 wt. % 95.46wt. % 6.5 5% TAIC 1% APES Precipitate Precipitate (UV × 8 + 120° C. 5min) 99.03 wt. % 98.12 wt. % 6.6 5% TAIC 1% APES Precipitate Precipitate(UV × 10 + 120° C. 5 min) 98.29 wt. % 99.08 wt. %

TABLE 7 Influence of wavelength (H-Bulb and D-Bulb) on UV crosslinkingof PFE-1 + Alkene + Amine H-Bulb, UV 10 D-Bulb, UV 10 times + 120° C. 5min times + 120° C. 5 min Comparative Example D 5% Fluorinated etherdiene Viscosity Soluble 2% 1173 Control builds up Examples 7.1 5% TAICPrecipitate Precipitate 0.5% APES 96.98 wt. % 97.02 wt. % 7.2 5% TAICPrecipitate Precipitate 1% APES 98.29 wt. % 99.08 wt. % 7.3 5% TAICPrecipitate Precipitate 0.5% N—Me-APMS 94.77 wt. % 91.47 wt. % 7.4 5%TAIC Precipitate Precipitate 1% N—Me-APMS 95.98 wt. % 97.88 wt. % 7.5 5%TAIC Precipitate Precipitate 0.5% N,N-DiMe-APMS 97.85 wt. % 98.36 wt %7.6 5% TAIC Precipitate Precipitate 1% N,N-DiMe-APMS 98.37 wt. % 98.28wt. % 7.7 5% Fluorinated ether diene Precipitation Precipitation 1% APES90.64 wt. % 87.25 wt. % 7.8 5% Fluorinated ether diene PrecipitationPrecipitation 1% N—Me-APMS 87.13 wt. % 84.30 wt. % 7.9 5% Fluorinatedether diene Precipitation Precipitation 1% N,N-DiMe-APMS 91.95 wt. %88.62 wt. % 7.10 5% Fluorinated ether diene Precipitate Precipitate 0.5%APES 2% 1173 88.11 wt. % 85.92 wt. % 7.11 5% Fluorinated ether dienePrecipitate Precipitate 1% APES 2% 1173 94.40 wt. % 95.17 wt. % 7.12 5%Fluorinated ether diene Precipitate Precipitate 0.5% N—Me-APMS 2% 117381.26 wt. % 81.39 wt. % 7.13 5% Fluorinated ether diene PrecipitatePrecipitate 1% N—Me-APMS 2% 1173 89.13 wt. % 88.61 wt. % 7.14 5%Fluorinated ether diene Precipitate Precipitate 0.5% N,N-DiMe-APMS 2%1173 90.33 wt. % 91.51 wt. % 7.15 5% Fluorinated ether diene PrecipitatePrecipitate 1% N,N-DiMe-APMS 2% 1173 92.82 wt. % 94.89 wt. %

TABLE 8 Effect of an aminosilane ester on photochemically crosslinkingPFE-2 with alkenes UV cured 10 Thermally cured times + 120° ExampleAllyl silane at 120° C. 5 min C. 5 min 8.1 5% ATES 1% APES Soluble Swell81.19 wt. %

TABLE 9 Influence of wavelength (H-Bulb and D-Bulb) on UV crosslinkingof PFE-2 + TAIC H-Bulb, UV 10 D-Bulb, UV 10 times + 120° times + 120°Example C. 5 min C. 5 min 9.1 5% TAIC 1% APES Swell, Swell, 82.28 wt. %83.87 wt. %

TABLE 10 Photochemically crosslinked PFE-1 (UV cure only or UV + thermalcure) at 120° C. for 5 minutes UV + 120° Example UV only C. 5 min 10.15% TAIC 1% APES (UV × 4) Precipitate Precipitate 86.50 wt. % 97.72 wt. %Preparation of Fluoropolymer Solution with Dispersed CrystallineFluoropolymer Particles:

Perfluoroelastomer latex PFE-1 was mixed with crystalline fluoropolymerlatexes PFA, PTFE, or with THV respectively at the weight ratiosdescribed in the Table 11. The solutions were vortex mixing for 1-2minutes. Subsequently, the well-mixed solutions were froze at −20° C.temperature for 4 hours, and then taken out and thawed in warm water.After thawing, the precipitates were filtered and washed with deionized(DI) water. The obtained solids were dried in an oven at 100° C. for 1-2hours. The dried coagulated solids were mixed with HFE to form a 10 wt.% solution in HFE. TAIC and APS was also added to the HFE composition asindicated in Table 11. Each composition was placed in a shaker for 3-4hours obtaining a stable and well-dispersed homogeneous composition.

Samples were prepared by depositing a 3 g solution onto PET film. Thecoated film was dried at ambient temperature for 2 hours and at 50° C.for 20 min. After the samples were completely dried, the PET filmsamples were placed on a wooden or a stainless steel board and curedunder a single 500 watt H-bulb for 5-10 runs with a speed of 30 ft perminute (as indicated in the tables). After UV curing, some samples werealso thermally cured at 120° C. for 5 min an oven (as indicated in Table11).

The UV cured samples (1-2 mils in thickness) were peeled off from thePET film, weighed, and then dissolved with HFE in a vial. The mass ratioof cured PFE sample/HFE solvent was 5/95. The vial was subjected tovigorous shaking overnight (˜12 hours) before any observation wasrecorded as described in the following table. The precipitated samples(i.e. crosslinked PFE) in the HFE solutions were collected, dried andweighed.

TABLE 11 Crystalline Fluoropolymer Particles Coated with PhotochemicallyCrosslinked PFE-1 UV cured UV cured 10 times + Example 10 times 120° C.5 min 11.1 PFE-1/THV340 (70:30) 82.34 wt. % 92.81 wt. % 2.5% TAIC 1% APS11.2 PFE-1/THV-2 (70:30) 89.92 wt. % 94.30 wt. % 2.5% TAIC 1% APS 11.3PFE-1/THV-1 (70:30) 91.35 wt. % 96.32 wt. % 2.5% TAIC 1% APS 11.4PFE-1PFA (70:30) 93.58 wt. % 96.65 wt. % 2.5% TAIC 1% APS 11.5PFE-1/PTFE (70:30) 92.11 wt. % 94.21 wt. % 2.5% TAIC 1% APSTable 12. Effect of an aminosilane ester on UV curing of PFE-1

Perfluoroelastomer PFE-1 solutions were prepared by cutting gumsseparately into small pieces and adding them into HFE solvent (HFE-7300or HFE-7500) to make a 10 wt. % PFE in HFE solution (10 g PFE and 90 gHFE) as described above. The aminosilanes, alkoxy silanes, and 1173 weredissolved or dispersed in HFE to form 1 wt. % or 5 wt. % solutions orsuspensions and combined with PFE-1 solutions as described above.

UV cured for 10 runs + Thermally cured at Thermally cured at 120° C. for5 minutes 120° C. for 5 minutes Primary Amino silane Ex. 12-1 - 0.5%APES Soluble Viscosity builds up Ex. 12-2 - 1% APES Soluble Gel 64.75wt. % Ex. 12-3 - 1.5% APES Soluble Swell 84.72 wt. % Ex. 12-4 - 3% APESSoluble Precipitate 86.06 wt. % Ex. 12-5 - 5% APES Soluble Precipitate88.33 wt. % Ex. 12-6 - 3% APES 2% TEOS Soluble Precipitate 86.80 wt. %Ex. 12-7 - 3% APES 2% TMOS Soluble Precipitate 83.59 wt. % Ex. 12-8 -1.5% APES 1% 1173 Soluble Swell 87.53 wt. % Ex. 12-9 - 3% APES 1% 1173Soluble Precipitate 91.26 wt. % Ex. 12-10 - 3% APES 2% 1173 SolublePrecipitate 86.69 wt. % Ex. 12-11 - 5% APES 2% 1173 Soluble Precipitate87.92 wt. % Ex. 12-12 - 5% APES 5% 1173 Soluble Precipitate SecondaryAmino silane Ex. 12-13 - 5% N-ME-APMS Soluble Gel 85.60 wt % Ex. 12-16 -5% N-ME-APMS 0.5% APES Soluble Precipitate 80.61 wt % Ex. 12-17 - 5%N-ME-APMS 1% APES Soluble Precipitate 81.68 wt %

TABLE 13 Effect of an aminosilane ester on UV curing PFE-2 UV cured for10 Thermally cured runs + Thermally at 120 C. cured at 120 C. PrimaryAmino silane for 5 minutes for 5 minutes Ex. 13-1 -5% APES Viscosityincrease Swell, 88.94 wt %

Some of the compositions of Examples 12-1 to 13-1 were cured with aD-bulb instead of an H-bulb and provided similar crosslinking results.

General Procedure—Compounded Fluoropolymers (CFP) Having InorganicFillers:

Compounded fluoropolymers (CFP) were prepared by combining 10 ofperfluoroelastomer with fillers according to Table 14 using conventionalrubber processing equipment to provide well-mixed, solid mixtures ofperfluoroelastomer and filler. Glass bubbles were treated with afluorinated hydrophobic surface treatment prior to use.

TABLE 14 Compound Fluoropolymers (CFP) Prepared CFP Description CFP-1Compounded fluoropolymer of PFE-3 with FG-Si at 70/30 by weight CFP-2Compounded fluoropolymer of PFE-3 with FG-Si at 50/50 by weight CFP-3Compounded fluoropolymer of PFE-3 with FG-Si at 80/20 by weight CFP-4Compounded fluoropolymer of PFE-3 with glass bubble at 80/20 by weightCFP-5 Compounded fluoropolymer of PFE-3 with FS20 at 70/30 by weightCFP-6 Compounded fluoropolymer of PFE-3 with FS550 at 70/30 by weightCFP-7 Compounded fluoropolymer of PFE-1 with FG-Si at 70/30 by weightCFP-8 Compounded fluoropolymer of PFE-1 with glass bubbles at 80/20 byweight

SRC220 Surface Treated Glass Bubbles

A solution was prepared by adding 9 g of 3M Stain Resistant AdditiveSRC220 (an aqueous fluorinated polyurethane dispersion, 15% solids) to50 g DI water, stirring for 5 minutes, and transferring the solution toa 60-mL syringe with a 18 gauge needle syringe.

To a 1-gallon size Lodige Popenmier mixer was added 900 g of iM16K glassbubbles. The surface treatment solution was sprayed while mixing at a400 rpm mixing rate. After mixing at room temperature for 15 minutes,the mixing vessel was heated to 120-130° C. for 1.5 hrs.

General Procedure for Coatings from PFE-3 and CQ0382 or CQ1082:

PFE coating solutions were prepared as generally described above toobtain 9 wt. % solutions in HFE. The fused silica fillers wereseparately dispersed in the HFE with a high-speed mixer to form 50 wt. %solids dispersions. The PFE solution and fused silica dispersion werecombined with each other followed by addition of the curing agent,alkoxy silane, and glass fibers. PFE composite films were obtained bycoating the solutions with a comma bar coater having a 300 um to 350 umgap. The obtained coatings were coated onto a release liner (precoatedwith a fluorinated release coating) and then dried in a 100° C. oven toremove solvents. The films were then separated from the liners andplaced into a Teflon coated metal tray and baked at 160° C. to 200° C.to crosslink the system. The thickness of the obtained films ranged from230 um to 290 um. The films were characterized with different testmethods. The concentration of the components (i.e. solids) and resultsare summarized in Tables 15 to 17.

TABLE 15 PFE-3 compositions and CTE results CTE CTE PFE-3 CQ0382 BTESPATEOS QF (50° C.- (90° C.- Example (g) (g) (%) (%) (%) 90° C.) 130° C.)15.1 40 60 4.8 1.5 0 60 108 15.2 40 60 4.8 0.6 0 39  86 15.3 40 60 4.80.3 0 37  79 15.4 40 60 4.8 0.6 0.3 34  56 15.4 50 50 6 0.6 0 60  9615.5 60 40 7.2 0.6 0 39  80

TABLE 16 Dielectric constant (Dk), Dissipation loss (Df), T-peel fromCopper, and Static Water Contact Angle results of PFE-3 compositionsT-Peel from Water Contact Example Dk Df Copper Angle 15.1 2.45 0.00190.6 N/mm 103-106° 15.2 2.37 0.0018 0.6 N/mm 103-106° 15.3 2.24 0.00170.6 N/mm 103-106° 15.4 1.98 0.002 0.6 N/mm 103-106° 15.5 2.23 0.0019 0.6N/mm 103-106°

TABLE 17 PFE-3 compositions with different silica size and CTE resultsCTE PFE-3 CQ0382 CQ1082 BTESPA TEOPS (50° C.- Example (g) (g) (g) (%)(%) 90° C.) 17.1 30 70 0 3 0.3 4 17.2 30 0 70 3 0.3 95General Procedure for Coatings from PFE-3 and Fused Silica (SF550):

A solution of PFE-3 with fused silica in HFE was prepared as describedgenerally above using PFE-3 gum (20 g, cut in small piece), 3M fusedsilica (8.6 g, FS550), and HFE (290 g). The stable coating solution had6.45 wt % of PFE-3, and the ratio of PFE-3 to FS550 was 70/30 by weight.Similarly, a 6.45% coating solution of PFE-3 with fused silica at 80/20by weight was prepared using 20 g PFE-3, 6.0 g FS550 and 290 g HFE.

All crosslinkers (e.g. BTESPA) were dissolved in HFE to form 5% or 10%solutions. 3% to 5% BTESPA crosslinker was formulated in PFE-3/FS550solution based on the PFE amount. Alkoxy silane compounds wereformulated with PFE-3/FS550 solution based on the weight of FS550 asshown below. After fully mixing, the solution was coated on either RLFilm or DuPont PFA film at different thicknesses and then cured at 140°C. in an oven for 5 hours. The coatings on release liner were removedfrom the liner prior to testing, and the coatings on PFA film weretested directly on the PFA film. CTE was tested from films released fromliner. The formulations and test results are summarized in Tables 18 and19. For some examples, moisture uptake (23° C./5-95% RH) was measured.The moisture uptake of sample 18.6 was 0.11%.

TABLE 18 Coating Compositions from PFE-3 and SF550 Fused Silica PFE-3FS550 Alkoxysilane Example (g) (g) BTESPA Compound Substrate 18.1 95  5%RL Film 18.2 70 30 1.5% 3% C4-Si RL Film 18.3 70 30 1.5% PFA 18.4 70 30 3% PFA 18.5 70 30 1.5% 3% HFPO-Si PFA 18.6 70 30 1.5% 3% C6-Si PFA 18.770 30  3% 1% TEOS PFA

TABLE 19 Testing Results of Coating Compositions from PFE-3 and SF550Fused Silica Thickness CTE CTE Example (um) Dk Df (5-30° C.) (50-60° C.)18.1 110 0.0022 18.2 41 2.35 0.0022 102.7 18.3 12 0.0009 18.4 17 0.000818.5 15 0.0009 18.6 15 0.0009 111 126 18.7 10 0.0014Coatings from Compounded Fluoropolymers:

For coating solution formulations, all CFPs (20 g, cut in small piece)were first dissolved in HFE (180 g) to obtain a 10% solution aftershaking vigorously overnight in a sealed glass bottle. All crosslinkers(e.g. BTESPA) were dissolved in HFE to have 5% or 10% solution. Allcrosslinkers were formulated in CFP solutions based on the total weightof CFP as shown in Table 20. After fully mixing, the solution was coatedon either RL Film or DuPont PFA film or FEP film at different thickness,then cured in a 140° C. oven for 5 hours prior to testing. The coatingson release liner were removed from the liner prior to testing, and thecoatings on PFA film were tested directly on the PFA film. CTE wastested from films released from liner. The results are summarized inTables 20 and 21. For some of the examples, moisture uptake (23°C./5-95% RH) was measured. Two examples that exhibited good moistureuptake were 20.12 and 20.14, that had moisture uptakes of 0.15% and0.13%, respectively.

TABLE 20 Compounded Fluoropolymer Coating Formulations Alkoxy SilaneExample CFP BTESPA Compound Substrate 20.1 CFP-1, 97% 1.5% 1.5% TEOS FEP20.2 CFP-1, 96%  3% 1% TEOS PFA 20.3 CFP-1, 98%  1% 1% TEOS PFA 20.4CFP-1, 98%  1% 1% TEOS RL Film 20.5 CFP-1, 95% 1.5% 5% HFPO-Si RL Film20.6 CFP-2, 95%  5% PFA 20.7 CFP-2, 95% 1.5% 5% HFPO-Si PFA 20.8 CFP-2,95% 1.5% 5% C6-Si PFA 20.9 CFP-3, 97% 1.5% 1.5% TEOS FEP 20.10 CFP-4,95% 2.5% 2.5% TEOS FEP 20.11  CFP-5, 100% 1.5% PFA 20.12 CFP-5, 95%  5%PFA 20.13  CFP-6, 100% 1.5% PFA 20.14 CFP-6, 95%  5% PFA

TABLE 21 Dk, Df and CTE of Compounded Fluoropolymer Coatings ThicknessCTE CTE Example (um) Dk Df (5-30° C.) (60-75° C.) 20.1 7 2.60 0.002420.2 8 0.0016 20.3 8 0.0024 20.4 125 0.0023 20.5 83 0.0022 20.6 6 0.003420.7 7 0.0024 20.8 7 0.0024 20.9 6 2.36 0.0023 20.10 22 0.0028 20.11 100.0013 20.12 11 0.0018 110 154 20.13 8 0.0014 20.14 9 0.0018 128 181

Compounded Fluoropolymers Coatings Cured by UV:

The 10% coating solutions of compounded fluoropolymers with (e.g.silica) inorganic fillers were prepared as generally described abovefrom 20 g PFE-1 based CFP gum (cut in small pieces) and 180 g HFE aftershaking vigorously overnight at room temperature in a sealed glassbottle. Crosslinkers (BTESPA and TAIC) were dispersed in HFE to yield a5% solution. All crosslinkers (BTESPA and TAIC) were formulated in CFPsolution based on the total weight of CFP as shown below. After fullymixing, the solution was coated on either DuPont PFA film or FEP film atdifferent thicknesses. The coatings were first dried in a 100° C. ovenfor 5 minutes, then cured with H-bulb UV at 100% power under nitrogen bypassing 10 times at 30 fpm. The results are summarized in Table 22.

TABLE 22 Compounded Fluoropolymer Coatings Formulations and Dk/Df/CTEResults Thickness Example CFP BTESPA TAIC TEOS Substrate (um) Dk Df 22.1CFP-7, 95.5% 1.5% 3% FEP 8 2.53 0.0026 22.2 CFP-7, 96%    1% 3% PFA 160.0020 22.3 CFP-8, 97.5% 1.5% 1% PFA 16 0.0027General Procedure for Coatings from PFE-3 and Silica Particles:

PFE coating solutions were prepared as generally described above toobtain 5 wt. % PFE-3 solutions in HFE-7300. The fused silica fillerswere separately dispersed in the HFE with a high-speed mixer to form 50wt. % solids dispersions.

Bis(3-trimethoxysilylpropyl)amine (BTMSPA) was dissolved or dispersed inHFE-7300 to form 10 wt. % solutions or suspensions. To the PFE-3solution were added BTMSPA and silica particle as indicated in Table 23.The BTMSPA in HFE-7300 solution was homogenized using a vortex shaker at1000 revolutions per minute (rpm) for 10 seconds to form a welldispersed slurry before being added to the PFE-3/HFE-7300 solution. Thepercentage indicated in the formula (e.g., 5%, 2%) was the mass fractionbased on the solid content of PFE-3. For instance, PFE-3+5% BTMSPAmeans: the solid content of PFE-3/APES=95:5. The prepared solutionsdescribed above were typically stirred under vortex for 1-2 minutes at2500 rpm. All above prepared solutions were coated on clean PET releaseliner or copper foil with a No. 24 Meyer rod, and the resulting coatingswere normally cured at 165° C. for 20 minutes to 1 hour. The cured filmswere released from the liner and were evaluated for Dk, Df, moistureuptake, and CTE.

TABLE 23 Perfluoropolymer Composite Coatings Formulations andDk/Df/Moisture Uptake/CTE Results Moisture CTE (5- CTE (60- ExampleFormulation Dk Df uptake 30° C.) 145° C.) 23.1 PFE-3/BTMSPA 2.35 0.0022(95/5) 23.2 PFE- 2.36 0.0028 0.15% 3/GB/BTMSPA/TEOS (80/20/2.5/1.5) 23.3PFE-3/FG- 2.36 0.0028 0.15% 5 Si/BTMSPA/TEOS (70/30/1.5/1.5) 23.4PFE-3/FS 20/BTMSPA 2.36 0.0018 0.15% 110 154 (70/30/5) 23.5 PFE-3/FS550/BTMSPA 0.0014 (70/30/1.5) 23.6 PFE-3/FS 550/BTMSPA 0.0018 128 180(70/30/5) 23.7 PFE-3/FS 550/C4- 0.0020 0.09% 128 181 Si/BTMSPA(70/30/1.5/1.5)

General Procedure for Perfluoroelastomer-Perfluoropolastic NanoparticleDispersion Coating Solution Preparations: PFE-PFA or PFE-PTFECoagulations & Dispersion Solution Preparations

Perfluoroelastomer PFE-3 (30.5 wt %), was co-coagulated with PFA latex(30 wt % PFA-2 latex) or with a PTFE latex (30 wt % obtained from thedilution of 55 wt % TFM-2 latex) in the ratios described in Table 24.The latex solutions were mixed and were put on a roller for 20 minutes.Subsequently, the well-mixed solutions were frozen in a fridgeovernight. They were taken out and thawed in warm water or in an oven at60° C. After melting, the precipitates were filtered and washed withdeionized (DI) water at least three times. The obtained solids weredried in an air-circulated oven at 55-65° C. overnight. The driedPFE/PFA-2 and PFE/PTFE co-coagulated solids were mixed with HFE-7300separately in 5-20 wt % solutions. They were placed in a shaker or aroller at a speed of 80 cycles/minute overnight or longer to obtainstable and well-dispersed solutions in HFE-7300 (Table 24).

General Procedure for Perfluoropolymer Coating Solution PreparationsOptionally with Aminosilane Ester or Fluorinated Amidine Curatives andInorganic Fillers Including Spherical Silica, Fiber Glass Particles andBoron Nitride Particles for Coatings, Electric Property Measurements andCopper Bonding Adhesion Measurements:

PFE-3, PFE-3/PFA-2 or PFE-3/PTFE were dissolved/dispersed in HFE-7300 bycutting the fluoropolymer materials into small pieces and placing theminto separated glass jars and adding HFE-7300 solvent to each of theglass jars. The containers were well sealed with PTFE tape and paraffinfilm. The solution was then subject to vigorous shaking overnight (˜12hours) to obtain a completely homogenous solutions of 5-8 wt % PFE-3 inHFE-7300 (e.g., 5 g PFE-3 and 95 g HFE-7300), 10 wt % PFE-3/PTFE orPFE-3/PFA-2 in HFE-7300.

To the PFE-3, PFE-3/PTFE or PFE-3/PFA-2 dispersion solutions wereseparately added BTMSPA, an aminosilane, or a fluorinated amidinecurative, in a percentage described in Table 24 for preparingperfluorinated polymer HFE solutions for coatings. In the case ofcoating solutions containing inorganic fillers, inorganic fillers ormixed fillers were weighed in glass jars separately, and to each of theinorganic fillers or mixed fillers was added a small amount of HFEsolvent and vortexed for 1-2 minutes. To the HFE-7300 filler or mixedfiller slurries were individually added the amounts of the aboveprepared fluoropolymer HFE solutions and curatives in ratios describedin Table 24.

An alternative way to prepare the above described inorganicfiller-containing fluoropolymer-HFE solutions was to first mixfluoropolymers PFE-3, PFE-3/PFA-2 or PFE-3/PTFE with one or moreinorganic fillers in ratios and subsequently add the amount of HFE-7300to make certain wt % solution concentrations described in Table 24. Theresulting prepared solutions were placed a shaker or a roller at a speedof 80 cycles/minute overnight or longer. The resulting solutions werehomogenous. Aminosilane BTMSPA or other curatives were added to thefreshly prepared fluoropolymer-inorganic filler-HFE-7300 solutions inratios described in Table 24. Also, the percentage in the formula (e.g.,5%, 2%) was the mass fraction based on the solid content of PFE-3. Forinstance, PFE-3+5% BTMSPA means: the solid content of PFE-3/APES=95:5.The prepared solutions described above were typically stirred undervortex for 1-2 minutes at 2500 rpm. All above prepared solutions werecoated on 3M release liner with a No. 24 Meyer rod or simply poured thesolutions onto the liner to obtain thicker coating samples, and theresulting coatings were normally dried at room temperature overnight orcured 120-165° C. for 20-105 minutes. The cured films were released fromthe liner and were available for adhesion to copper, Dk/Df measurementsand CTE measurements shown in in Table 24.

Perfluoropolymer solutions were coated on a release liner and dried atroom temperature overnight or cured at 120-165° C. for 30-105 minutes.The resulting films with an average 15-40 micron thickness were releasedfrom the liner and subsequently laminated against Cu foil in a Sandwichstructure for bonding at temperatures indicated in the tables and under1-2 ton pressure for normally 30 minutes.

TABLE 24 Cu-Bondable Perfluorinated Polymer Films Obtained by CoatingLamination Cu Peel Dk/Df, CTE, 2^(nd) Heat, Example Formulationcondition, ° C. force, N/cm 25 GHz μm/(m · ° C.) 24.1 Control PFA film310 <2    /0.0006- 0.0009 24.2 [PFE-3/PFA-2 (6:4)]/BN 200 8.9    /0.0018119 CFP 012/BTMSPA (80/20/3) 24.3 [PFE-3/PFA-2 (6:4)]/BN 200 5.8   /0.0013 119 CFP 012/fluorinated amidine (80/20/3) 24.4 [PFE-3/PFA-2(6:4)]/BN 200 7.9    /0.0018 127 CFP 0075/BTMSPA (80/20/3) 24.5[PFE-3/PFA-2 (6:4)]/BN 5.4    /0.0013 186 CFP 0075/fluorinated amidine(80/20/3) 24.6 [PFE-3/PFA-2 Not tested    /0.0028 129 (6:4)]/FT9110/BNCFP 012/BTMSPA (60/20/20/4) 24.7 [PFE-3/PFA-2 9.2    /0.0037 76(7:3)]/FT9110/BN CFP 012/BTMSPA (50/25/25/4) 24.8 63.5% PFE-3/PFA-2(7/3) + 200 6.9 28.6% BN CFP 012 + 4.8% FT9114 + 4% BTMSPA 24.9 66.7%PFE-3/PFA-2 (7/3) + 200 7.3 2.14/0.0019 75 28.6% BN CFP 012 + 4.8%FT9114 + 4% BTMSPA 24.10 70% PFE-3/PFA-2 200 20.8 2.20/0.0042 16(70/30) + 23% FT9114, 5% BTMSPA + 2% C-6Si 24.11 70% PFE-3/PFA-2 20019.8 2.04/0.0055 111 (70/30) + 23% FG6616, 5% BTMSPA + 2% C-6Si 24.1270% PFE-3/PFA-2 200 17.1 1.92/0.0052 30 (70/30) + 23% FG6608, 5%BTMSPA + 2% C-6Si 24.13 70% PFE-3/PFA-2 200 22.1 2.31/0.0044 106(70/30) + 23% FG3004, 5% BTMSPA + 2% C-6Si 24.14 70% PFE-3/PFA-2 20016.9 2.67/0.0033 108 (70/30) + 23% Wallonites + 5% BTMSPA + 2% C-6Si24.15 40% PFE-3/TFM-2 (60/40), 200 6.7 2.58/0.0016 61 60% CQ0382, 5%BTMSPA 24.16 65% PFE-3/PFA-2 200 5.5 (70/30), 28% GB, 5% BTMSPA, 2%C-6Si 24.17 60% PFE-3/TFM-2 200 8.9 2.18/0.0023 161 (60/40) + 35%CQ0382 + 5% FT9114 + 1.5% PFE301C + 5% BTMSPA 24.18 [PFE-3/PFA-2 20011.5    /0.0040 75 (7:3)]/FT9110/BTMSPA (60/40/3) 24.19 [PFE-3/PFA-2 20011.4    /0.0049 69 (7:3)]/FT9110/BTMSPA (50/50/3) 24.20 [PFE-3/PFA-2(7:3)]/BN 200 2.85/0.0015 113 CFP 0075/CQ0382/BTMSPA (50/15/35/4) 24.21[PFE-3/PFA-2 (7:3)]/BN 200 2.08/0.0014 82 CFP 0075/CQ0282/BTMSPA(50/15/35/4) 24.22 [PFE-3/PFA-2 200 120 (7:3)]/FT9110/CQ0282/BTMSPA(50/15/35/4) 24.23 [PFE-3/PFA-2 200 2.95/0.0030 133(7:3)]/FT9110/CQ0382/BTMSPA (50/15/35/4) 24.24 [PFE-3/PFA-2 2002.83/0.0038 92 (7:3)]/FT9110/CQ0282/BTMSPA (50/25/25/4) 24.25[PFE-3/PFA-2 200 2.69/0.0049 108 (7:3)]/FT9110/CQ0382/BTMSPA(50/25/25/4)General Procedure for Perfluoropolymer Coating Solution Preparationswith Inorganic Fillers:

Solutions containing co-coagulated perfluoropolymers and one or moreinorganic filler (e.g. silica nanoparticles, quartz fibers and boronnitride) are referred to as fluoropolymer resins and weredissolved/dispersed in HFE-7300. The Solutions were prepared in thefollowing stepwise procedure: The dry inorganic and fluoropolymer resinwas combined in a container and HFE-7300 was added. The container wasthen sealed and placed on a roller to gently agitate overnight or longeruntil the solution was determined to be completely mixed and ready forcoating. The solution was then subsequently transferred to a shearmixing container and mixed at 2500-3500 rpm for 3-4 minutes. To the wellmixed solution, BTMSPA was added (5% mass of resin in solution). Afterthe BTMSPA was added, the solution was vortexed for thorough mixing andthen placed on a shaker for 30-60 minutes. The solution is then coatedon release liner using a No. 24 Meyer rod and tape guides to control thefilm thickness. The films were air dried at room temperature andsubsequently removed from the release liner and thermo-cured at 165° C.for 1 hour. The cured samples were then ready for testing.

TABLE 25 Perfluorinated Polymer Composite Coatings* Dk/Df (25 GHz) CTECTE CTE CTE Cu tan (1st (2nd (1st (2nd Example Formulation Bonding eps′delta MD) MD) TD) TD) 25.1 PFE-3/PFA-3  8.7-12.3 2.38 0.0018 177 14 10518 (7:3)/FS 550/QF [67:28:5] 25.2 PFE-3/PTFE5033 10.1-11.4 2.50 0.002266 14 175 29 (7:3)/FS 550/QF [67:28:5] 25.3 PFE-3/PFA-3 10.3-12.6 2.410.0019 109 11 110 26 (7:3)/FS 550/CQ0382/FT9114/QF [60:16:16:4:4] 25.4PFE-3/PTFE5033 13.2-17.4 2.52 0.0022 154 20 84 18 (7:3)/FS550/CQ0382/FT9114/QF [60:16:16:4:4] *Average film thickness of 100microns.

TABLE 26 Perfluorinated Polymer Composite Coatings* Dk/Df (25 GHz) CTECTE CTE CTE Cu tan (1st (2nd (1st (2nd Example Formulation Bonding eps′delta MD) MD) TD) TD) 26.1 PFE-3/PFA-2 8.1 2.77 0.0011 133 13 215 22(7:3)/BN CFP 012/QF [60:37:3] 26.2 PFE-3/PFA-2 8.0 2.71 0.0014 210 12141 18 (7:3)/BN CFP 012/QF/FT9114 [60:34:3:3] 26.3 PFE-3/PFA-2 11.2 2.760.0013 163 14 168 43 (7:3)/BN CFP 012/CQ0382/QF [60:18.5:18.5:3] 26.4PFE-3/PFA-2 10.8 2.72 0.0016 106 13 90 31 (7:3)/BN CFP012/CQ0382/QF/FT9114 [60:17:17:3:3] 26.5 PFE-3/PFA-2 13.2 2.67 0.0014179 37 191 17 (7:3)/BN CFP 012/CQ0382/QF [60:12.3:24.7:3] 26.6PFE-3/PFA-2 13.6 2.69 0.0017 72 17 112 27 (7:3)/BN CFP012/CQ0382/QF/FT9114 [60:11.3:22.7:3:3] *Average film thickness of100-130 microns.

1. An electronic telecommunication article comprising a crosslinkedfluoropolymer layer, wherein the fluoropolymer comprises at least 80,85, or 90% by weight of polymerized units of perfluorinated monomers andcure sites; wherein the article is an integrated circuit, printedcircuit board, an antenna, or an optical cable.
 2. The electronictelecommunication article of claim 1 wherein the crosslinkedfluoropolymer layer is a substrate, patterned (e.g. photoresist) layer,insulating layer, passivation layer, cladding, protective layer, or acombination thereof. 3-4. (canceled)
 5. The electronic telecommunicationarticle of claim 4 wherein the antenna is an antenna of a computerdevice or an outdoor structure.
 6. (canceled)
 7. The electronictelecommunication article of claim 1 wherein the crosslinkedfluoropolymer layer has i) a dielectric constant (Dk) of less than 2.75,2.70, 2.65, 2.60, 2.55, 2.50, 2.45, 2.40, 2.35, 2.30, 2.25, 2.20, 2.15,2.10, 2.05, 2.00, 1.95; ii) a dielectric loss of less than 0.01, 0.009,0.008, 0.007, 0.006, 0.005, 0.004, 0.003, 0.002, 0.001, 0.0009, 0.0008,0.0007, 0.0006; or a combination thereof.
 8. The electronictelecommunication article of claim 1 wherein the fluoropolymer furthercomprises cure sites selected from nitrile, iodine, bromine, andchlorine.
 9. The electronic telecommunication article of claim 1 whereinthe perfluorinated monomers are selected from tetrafluoroethene (TFE)and one or more unsaturated perfluorinated alkyl ethers
 10. Theelectronic telecommunication article of claim 9 wherein the unsaturatedperfluorinated alkyl ether of the fluoropolymer has the general formulaR_(f)—O—(CF₂)_(n)—CF═CF₂ wherein n is 1 or 0 and R_(f) is aperfluoroalkyl or perfluoroether group.
 11. The electronictelecommunication article of claim 1 wherein the crosslinkedfluoropolymer is crosslinked with a curing agent is selected from i) aperoxide and an ethylenically unsaturated compound; ii) one or morecompounds comprising an electron donor group and an ethylenicallyunsaturated group; or iii) an amino organosilane ester compound or esterequivalent.
 12. The electronic telecommunication article of claim 1wherein the curing agent comprises at least two ethylenicallyunsaturated groups or at least one ethylenically unsaturated group andat least one alkoxy silane group.
 13. (canceled)
 14. The electronictelecommunication article of claim 1 wherein the crosslinkedfluoropolymer is crosslinked with an amine curing agent.
 15. Theelectronic telecommunication article of claim 1 wherein thefluoropolymer comprises 40 to 60% by weight of polymerized units of TFEbased on the total weight of the fluoropolymer.
 16. The electronictelecommunication article of claim 1 wherein the crosslinkedfluoropolymer comprises no greater than 5, 4, 3, 2, 1 or 0.1 wt.-% ofpolymerized units derived from non-fluorinated or partially fluorinatedmonomers and/or comprises no greater than 5, 4, 3, 2, 1 or 0.1 wt. % ofester-containing linkages.
 17. The electronic telecommunication articleof claim 1 wherein the crosslinked fluoropolymer is insoluble in3-ethoxy perfluorinated 2-methyl hexane or 3-methoxy perfluorinated4-methyl pentane.
 18. The electronic telecommunication article of claim1 wherein the crosslinked fluoropolymer layer further comprisescrystalline fluoropolymer particles. 19-45. (canceled)
 46. Theelectronic telecommunication article of claim 1 wherein the crosslinkedfluoropolymer layer further comprises silica, glass fibers, or acombination thereof. 47-48. (canceled)
 49. The electronictelecommunication article of claim 1 wherein the crosslinkedfluoropolymer layer further comprises a thermally conductive filler. 50.The electronic telecommunication article of claim 46 wherein the silicais fumed silica, fused silica, glass bubbles, or a combination thereof.51. The electronic telecommunication article of claim 46 wherein thefumed or fused silica has an aggregate particle size of at least 500 nm,1 micron, 1.5 microns, or 2 microns.
 52. The electronictelecommunication article of claim 46 wherein the silica comprises ahydrophobic surface treatment optionally comprising a fluorinated alkoxysilane compound.
 53. The electronic telecommunication article of claim46 wherein the silica is present in an amount of at least 10, 20, 30,40, 50, 60, or 70 wt. % based on the total amount of the crosslinkedfluoropolymer layer. 54-61. (canceled)